For long videos Viddler offered several advantages over sites like Youtube.
- Viddler supports videos longer that 10 minutes, and up to 500mb in size.
- Viddler has timed comments, which allow you to annotate important moments in the video
- Viddler had streaming playback, which allowed you to jump to arbitrary times by clicking in the seek bar. Also, you could click on a comment and jump to that point in the playback. This is very useful for picking out highlights.
Since I originally compared Viddler and Youtube in September 2007, several things have happened. Firstly, Youtube added support for seekable playback. Download is still "progressive" but can be restarted at any point by clicking in the seek bar. Recently Viddler turned off streaming support in their player, saying that it was "expensive and unreliable". They plan to move to a progressive seek player similar to those now offered by Youtube and Google.
So while Viddler still supports timed comments, its no longer possible to jump to the comment time. This was a very useful feature and IMO a key differentiator between their offerings and the many other video sharing sites out there. Lets hope they get this fixed soon.
Update: Viddler have added progressive seek to their player, so you can now jump to any time in a video. It does seem to be more stable than the old streaming player.