aye, we can split clips that way, but that would require re-uploading the video file to the phone each time and then trimming it to the next bit which is time consuming and will drain your batteries really fast.
The way I have done my stuff in the past was record a full length vid, open it in the beta PC editor and play it full screen while doing a screen capture with my PCs graphics card and edit the playing video to show what I wanted it to be looking at while recording the screen. I've then put that footage into my vlog as a PIP so match the time of the helmet camera so the audio aligns. It is an awful clunky way to do it, but at the time it was my only option. It has issues doing that though as the video seems to play at a different speed so need to adjust that too.
The IOS app as being used in the video you linked to works far better than the Android app, I don't have any IOS products so have to use the unfinished Android crAPP. TBF, the Android app is getting better, but is lower priority to them apparently, and the bete PC editor is even lower priority, which to me is totally backwards.
I've never had any other 360 camera, the resolutions from them until now have not quite been good enough. Even the One X and Fusion are still a little lower quality than I would like, but it is just about good enough now.