Echo supports MP4 (including M4V) and QuickTime MOV video formats. If you have a video file in a different format that you want to upload to Echo, you have two choices:
1) Upload the video to YouTube and embed the YouTube player in your course item.
2) Convert the video file to MP4 before uploading it to Echo.
You can use a free tool called HandBrake to convert video files. (Download HandBrake here: https://handbrake.fr/downloads.php). Watch a 5-minute video on using HandBrake here: https://www.youtube.com/watch?v=zoMPbK139rA