I'm confused.
All my Nextbase dashcams have recorded a complete journey from start to finish. I'm currently running a 128Gb card, which is probably overkill for some, but it gives me up to 8 hours recording.
I did have course last year to upload some video of an idiot undertaking at speed but it was just a case of finding the particular 3 minutes clips. Joining them using Replay3 as the event spanned 2, then uploading to Sussex Police.
I had no need to go prodding buttons to save a special video as I knew it was being saved anyway.