Magisto supports all formats that are "natively" supported by iOS, Android and Windows OS.
Photo file types: JPG, JPEG, BMP, TIFF, PNG, non animated GIF
Video file types: 3GP, AVI, MOV, MP4, MPG, MTS, M2TS
Audio file types: MP3, M4P, WMA, ADTS, OGG, WAV, WAVE
The easiest way to upload large files is to upload via Google Drive/Photos.