Tried to watch Scott Guthrie video, buffering starts after about 4 minutes into the show. There are seem to be some issues with the smooth streaming servers or CDN servers or both.

There is an excerpt from the IE9 network capture (hope someone from MS could look at it and figure out what is causing it):

 

URL Method Result Type Received Taken Initiator Wait‎‎ Start‎‎ Request‎‎ Response‎‎ Cache read‎‎ Gap‎‎
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3243240000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3243240000) GET 200 video/mp4 161.58 KB 78 ms  298134 0 31 47 0 47580
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3243827664">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3243827664) GET 200 video/mp4 35.24 KB 78 ms  298134 0 47 31 0 47580
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3263260000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3263260000) GET 200 video/mp4 128.11 KB 1.81 s  300115 0 1763 47 0 43867
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3266118820">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3266118820) GET 200 video/mp4 29.43 KB 46 ms  300334 0 31 15 0 45412
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3283280000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3283280000) GET 200 video/mp4 189.85 KB 1.79 s  302112 0 1747 47 0 41886
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3284694784">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3284694784) GET 200 video/mp4 35.24 KB 46 ms  302206 15 16 15 0 43540
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3303300000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3303300000) GET 200 video/mp4 142.46 KB 4.13 s  304124 0 4088 46 0 37534
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3306057142">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3306057142) GET 200 video/mp4 29.43 KB 31 ms  304156 0 15 16 0 41605
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3324517007">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3324517007) GET 500 text/html 1.37 KB 4.02 s  306074 0 4025 0 0 35693
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3323320000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3323320000) GET 200 video/mp4 151.12 KB 3.19 s  308274 0 3167 31 0 34320
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3344137868">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3344137868)  (Aborted)  0 B < 1 ms (Pending...) 310115 0 0 0 0 35677
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3343340000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3343340000)  (Aborted)  0 B < 1 ms (Pending...) 311488 0 0 0 0 34304
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3344137868">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3344137868)  (Aborted)  0 B 31 ms (Pending...) 319506 31 0 0 0 26255
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(599000)/Fragments(video=3343340000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(599000)/Fragments(video=3343340000) GET 200 video/mp4 143.42 KB 109 ms  320520 16 31 62 0 25163
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(599000)/Fragments(video=3363360000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(599000)/Fragments(video=3363360000) GET 500 text/html 1.37 KB 4.04 s  320676 0 4040 0 0 21076
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3363360000">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(784000)/Fragments(video=3363360000) GET 200 video/mp4 116.18 KB 1.26 s  324763 0 1233 31 0 19765
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3366312925">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3366312925)  (Aborted)  0 B < 1 ms (Pending...) 327774 0 0 0 0 18018
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3387109296">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3387109296)  (Aborted)  0 B 16 ms (Pending...) 336791 16 0 0 0 8985
http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3404509750">http://smooth.ch9.ms/ch9/b4c5/2da38755-aaee-4ab3-afbb-9ef60112b4c5/BTCScottGuthrie.ism/QualityLevels(128000)/Fragments(audio=3404509750) (Pending...) (Pending...) (Pending...) (Pending...) (Pending...) (Pending...) 345792 0 0 0 0 0