Using the built-in media player for the N900, I cannot play ANY kind of video. I can see the thumbnails of the videos and they are displayed correctly, however, if I want to play a video file (also tried the videos captured with the camera) I always get a message that there were no codecs found - however, I installed all codec packs and it was working some weeks ago.
I'm using the latest CSSU and "Extra Decoders Support" v0.4.
There's no such thing as codec packs for N900, There's extra decoders support which you have installed.
Maybe try reinstalling extra decoders support and see if it works. Also you may need to refresh your media library by restarting trackerd (and removing databases).
Failing that you will need to recall what you did last that made it not work and as a last resort, reflash!
3 x Nokia N900 | 2 x 32GB TopRAM microSDHC class 10 inserted in two devices | 2 x SIM cards inserted in two devices.
N900/ Nokia N900 is not a phone/smartphone! its an internet tablet with phone functionality - so quit assuming its still a phone/smartphone when it isn't!!
I'm using the latest CSSU and "Extra Decoders Support" v0.4.