Wikipedia has been working on democratizing video for a long time now. It's been meaning to make video as big a part of Wikipedia as text and photos for five years or more, but it may only now be able to actually do it.
It is now rolling out a new HTML5 video player and editor that should make it easier for people to add video, add captions and so on.
Adding videos to Wikipedia articles has been possible for a while, but it was a cumbersome process. The new player should be improve that.
Wikipedia now relies entirely on WebM, the open source and patent free codec for all video, though older ones based on OGG Theora still work.
A big addition to the new video is the ability to add captions, which could be anything from a description to subtitles.