To check which version of ActivPanel you are using, please consult article 1477

ActivPanel 1

Audioaac, dra, cook, mp2, mp3, pcm
Videoavs, flv, H.264, mp2, mp4
 

ActivPanel 2 and ActivPanel 3

Audioaac, dra, cook, mp2, mp3, pcm
Imagebmp, jpg
Videoavs, flv, H.264, mp2, mp4
 

ActivPanel 4

Audioaac, mp3, flac, ogg, wav
Imagebmp, gif, jpeg, jpg, png
Videoavi, gif, mov, mp4, webM, 3gp
 

ActivPanel 4.5

Audio     aac, ac3, flac, mp3, ogg, wav
Imagebmp, jpeg, png
Videoavi, flv, gif, mov, mp4, webM, wmv, 3gp

ActivPanel 5 and ActivPanel 6

Audio                           aac, asf, avi, dat, divx, flv, mkv, mov, mpeg, mpg, mp3, mp4, m4a, tp, trp, ts, vob, wav, 3gp
Imagebmp, jpeg, jpg, png
Videoasf, avi, dat, divx, flv, mkv, mov, mpeg, mpg, mp4, rm, rmvb, tp, trp, ts, vob, wmv, 3gpp

ActivPanel i-Series

Audio          aac, mp3, m4a, wma
Imagebmp, jpeg, jpg, png
Video        avi, dat, mkv, mov, mpg, mp4, rm, rmvb, trp, ts, vob

NB: Some video formats may contain unsupported codecs.