Apple AppStore App Preview - mov format
.mov is a container format that encompasses a variety of codecs. .mov is also a file format, not streaming (which is presumably how video is distributed for the App Store.)

I'm still somewhat unsure of what backend is used by Apple for their video streaming, but I believe they use their own HLS backend, which uses the MPEG-4/H.264.

Note that Apple transcodes whatever you upload, so it doesn't really matter how you upload it–except for possible differences in upload times and whatever additional time is needed on their end to transcode it.