I think that an AGtube would be great. I could watch a video about how awesome somone is, or get good tips on games. But I'm sure people have already posted this on YouTube and can be found there.
Another good use would be to report bugs that you find, you can just show people instead of trying to explain in text.
A few games that have a story by AG have tutorials. They are uploaded through YouTube.
The reason is video streaming requires a lot of server power (It's why YouTube has thousands of servers), and AG doesn't have it. Videos also take a lot of space, which is reserved for flash games.
We could probably just set up a page with walkthroughs from YouTube and a few text-based walkthroughs.
Now that's a better idea. Thing is, what are the criterions for a good walkthrough to be shown on AG? They'd have to be tested first by admins before being shown.
Seeing as the walkthrough and tutorial purposes of this suggestion have been dealt with already time to focus on Seashark's newest "reason".
Why can't we use YouTube for that? I know there our community has little presence there so it'd be nice. Heck, Agent_86 used to have an AG Video Blog on YouTube for a little while back in 2008.