Why do some free lecture videos on iTunes start streaming while others do not?

I am viewing some of those classroom lectures that are available at no charge on iTunes. Some begin streaming within a few seconds. On some playlists, however, the vids don't seem to steam at all. I can download and play them, but I want to stream them.

?2009-08-15T19:02:32Z

Favorite Answer

It is all about network speed. The ones that play immediately are more compressed thus taking less time to stream.