I agree that software should not behave differently after 1 or 100 plays, but this is happening time after time.
I have a folder which I have been using for testing, it contains 1 each of, .ts, .mkv, .mts, .webm,.mp4, .wmv, .flv., .avi.
Dopus viewer is now glitched again, so Its hard to say what does work, but right now.
All third party codecs are uninstalled and all formats play in wmplayer (64bit) except for .flv.
in Dopus, the following formats play but with no video, .mkv, avi and .wmv. all other format now display code in the viewer (unrecognised). all the above file extensions are listed in the movie plugin.
When the viewer is functioning correctly, I can see that different codec's are running for the different formats, it seems that this switching between codec's is causes a problem, maybe a incompatible codec is called up causing a glitch and then that codec somehow becomes the preferred choice, so videos will not play again.
During a previous test, I found that quartz.dll was being called up to do the video rendering, and this was giving the same results as Dopus Viewer (audio with no video, black screen)
when I changed the default video rending to a different codec. video would play correctly every time in Graphstudionext64. but this did not fix the problem in Dopus.
I would have to wipeout windows again to do more testing to give a correct answer to what will play on a fresh install, I didn't take notes.