Ohhhh. I recorded some Modern Warfare Remastered gameplay and it was probably the best video I'd ever recorded. Too bad my Elgato software randomly failed to record the commentary. Sent them some nasty tweets that they never answered, lol. I've never been so dejected/angry in my life. Which is kinda sad.
Also, your best bet is to salvage the video with a new second half, possibly even joking about the original second half being gone. It became a running joke in my future COD 4 Remastered recordings for me because I was genuinely confused as to what I still had and what was gone, so I didn't know if it was safe to reference things so I had to keep reminding the "audience" in a half-joking, mostly annoyed way.