If you haven't seen it before I'd recommend watching some NXT, maybe start at Takeover 2 if you want something great but relatively recent.
The Monday Night War series was pretty good for the first few episodes, especially if you aren't too familiar with the details of what happened in the ratings war with Nitro. I haven't kept up with the last few episodes though, so I can't say much about their quality.
I also started watching the Rivalries: McMahon v. Austin series and that was alright too. The only downside with the "documentary" stuff is they re-use a lot of the same interviews in different videos and re-hash the same ideas constantly.
As for just the old matches they have up there, I haven't really gotten into those so someone else might be able to help with that.