FlexClip supports uploading various video formats (within 1G per file), including MP4 (H264), MOV, WEBM, M4V. 

If you receive a format-related error message when you upload a video clip, we recommend that you reformat it using the free online video converting tool: https://www.flexclip.com/tools/convert-video/. 

Many video files have the same format but different encoding methods, such as MPEG4 encoding in MP4 format, which may need to be transcoded before using it.