Videos in rmvb format cannot be played in mobile players.
Need to transcode or download a player.
Videos that iPhone can play
iPhone supports MP4, AVI, NAVI, DV-AVI, DIVX, MOV, ASF, WMV, RM, RMVB and other video formats.
iPhone video playback formats
Video playback
Supported video formats: H.264 video, up to 1080p, 60 fps; High Profile level 4.2 and AAC -LC audio up to 160 Kbps, 48kHz; stereo audio in .m4v, .mp4 and .mov file formats; MPEG-4 video up to 2.5 Mbps, 640 x 480 pixels, 30 fps; Simple Profile and AAC -LC audio, up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4 and .mov file formats; Motion JPEG (M-JPEG), up to 35 Mbps, 1280 x 720 pixels, 30 fps; ulaw audio and PCM stereo audio, the file format is .avi
Audio playback
Supported sound file formats: AAC (8 to 320 Kbps), Protected AAC (from iTunes Store ), HE-AAC, MP3 (8 to 320 Kbps), MP3 VBR, Audible (formats 2, 3, 4, Audible Enhanced Audio, AAX and AAX+), Apple Lossless, AIFF and WAV