How To: Using the Drupal Flowplayer Module
Flash and its associated players are all the rage (actually have been for quite some time), except for with the iPad that is. Obviously, you can embed video into your Drupal site in a number of ways.
You can use an external site like YouTube or Blip.tv using the Embedded Media Field Module or you can implement video on your own site using the FLV Media Player Module in conjunction with JW Player.
However, if you're seeking to do REALLY cool things with video then Flowplayer API is definitely the way to go. It's going to provide the greatest level of customization (that's customization that YOU'LL have to do), with the lowest amount of overhead, of the other modules I've worked with. You'll have to get into the PHP of your theme to implement, but once you start to learn it, you'll really start to think about radical things like Views based videos series driving Flowplayer to create dynamic playlists and other cool whiz-bang features.
UPDATE: In the video, I mention that Flowplayer is becoming the most popular open source flash player. This is debatable. I should have said it's "my" favorite player. Here are some trends and insights regarding the two most popular players.