Video is complex and streaming video even more so. When you use TelemetryTV's video capabilities the videos themselves are streamed and cached on devices. TelemetryTV expects videos in a specific format in order to efficiently play them. Devices also have limited capabilities for gracefully handling videos.
TelemetryTV will automatically convert videos that are uploaded to it if they are not in the precise format with the information needed to stream. This is a slow process and will limit your input video to a maximum of 1GB in size.
It's best if you convert the videos before uploading to TelemetryTV. This is a process known as transcoding. Specifically TelemetryTV needs videos to be in MP4 format with h.264 as the video codec and AAC as the audio codec. Further the video must have information attached to it that allows it be be streamed over HTTP and played by TelemetryTV.
The easiest way to transcode a video is to use ffmpeg. The command line for transcoding a video with ffmpeg is as follows:
ffmpeg -i input.mp4 -f mp4 -c:v h264 -c:a aac -movflags empty_moov+omit_tfhd_offset+frag_keyframe+default_base_moof+faststart output.mp4
Install ffmpeg and use this command on the command line to transcode your video, replacing input.mp4 and output.mp4 with the names of your video. Uploading the resulting file to TelemetryTV and it'll be ready to use once done.