WTF is with the size of the downloadable videos these days?

The latest Anders Hejlsberg vid is 37:58 mins long and 147MB in size.  But the Julie Larson vid at 41:47 mins, but is 618MB! 

I know they're coded at different sizes and bit rates, but is the improvement in quality worth it?  It ain't for me coz it takes about 5 hours to suck a 600MB file thru the tiny straw that attaches my PC to the interweb.

Is it possible to have vids at lower and higher quality to choose from for downloading?

See ya,
P