Hello everyone. I just joined to discuss this same problem.
I have a 504 which i bought to record from a sony "lipstick" helmet cam.
After recording, i found that some video can be downloaded to a computer and played back. Some video can only be viewed in the Archos itself! It also breaks up video into random "shorter" segments, which might be related.
I called Archos twice. They told me that unless i buy their camera, that some "other brand" cameras will confuse the 504 and it puts a lock on them.
When i download or try to play the video, it has a message on it that says "Copy Protected Video File. Can only be played by original recording device"
I get sound, but no video. Archos says they have no interest in having me email them a video to try figuring this problem out. NICE!!
Help me!! I have very important video on here that i need to get downloaded for our store. I am willing to pay someone to figure this out. I know nothing about codecs or any of this stuff.

Paul