Video versions of classes have historically met with mixed responses. One permanent video recording of my previous classes, Overview and Bracket Customization
, clocks in at exactly an hour and has had many views but over 2 years, an avg. of 268 views per month. While many express their appreciation for having this video recording, many others also state that having to watch an hour-long video is just ugh! and they would much rather have an audio recording that they could listen to while doing other things. And keep in mind that most of our classes are 90-120 min in length. I made this particular video recording available because this is one class that simply cannot be taught very well through only audio.
The drawbacks are almost all on the instructor's end. IIRC, the original source recording for the above class was a file almost 2GB in size, and that was with reasonably compressed H.264. So unless the instructor takes the time to re-encode, they face having to upload multiple gigabytes to YouTube or whatever their video host of choice. Also, going back and editing errors, removing long pauses, etc. is not so easy and straightforward in video as it is with a simple audio MP3, and will likely require a lengthy re-encoding step. So most will probably not bother, because most don't bother to do it right now with audio recordings.
But even before reaching this level, instructors don't currently even stream
their classes except very rarely. Streaming would be noticeably easier, and it could be Step 1 of providing a permanent video recording. They could simply stream the class as they taught it and then Twitch.tv would make the stream available for 7 days afterward. The instructor would also have the option of making the recorded stream permanent, and voila, a video of the class.