GrimmReaperNL
Like Andre I tend to used external tools to convert but I use Vimeo instead as there are far less adverts. Also saves using your own bandwidth and file space up. To that end we do have a plugin that will allow you to place your remote videos in your CPG gallery and it supports a number of providors including Youtube, Vimeo and many more - http://forum.coppermine-gallery.net/index.php/topic,60195.0.html
I have seen and tried the remote video plug-in. We hosted the video's on youtube a while back, but because of a couple of reasons we decided to host them ourselfs.
Your flv files were coded with the AVC codec and named as .flv
Your mp4 files were coded with MPEG-4 Visual codec and named as .mp4
Correct mp4 files should be coded with MPEG4 AVC codec and named as .mp4
See to me, because I had (have) no idea about containers and codecs. if a file says mp4, it's an mp4 xD
But I've seen what you're getting at and I kind of understand what you're talking about now. specially with the different video and audio tabs in handbrake.
So i've tried handbrake, made sure video was set to H.264 and audio to AAC aaand because I'm pigheaded I left qualities nice and high
http://avantcourir.nl/cpg/displayimage.php?album=159&pid=15234#top_display_mediaThis now works (for me at least) on Chrome, Firefox and android (default and chrome), but not in IE (tried IE9 and Slimbrowser) based browsers.