I have limited knowledge on the subject, but if the screen is black in the recording you won't be able to "fix" it. What method/app did you use to record the screen?
Most screen recorders are able to be detected by sites due to the method that they use to capture the frames. You may have come across sites that don't let you screenshot them, and most recorders will essentially (this is a simplified explanation) screenshot 30-ish times a second to create a video, which definitely isn't the most efficient way of doing it.
I personally use an app called AZ Screen Recorder (free on the Play Store) which lets me do things like record Snapchat pics/videos without telling the poster I've done so, etc. I've never tried it with a live OF broadcast (which I'm guessing is what you're talking about?), but it could possibly work... The method it uses to record tricks the phone/site into thinking it's displaying the screen elsewhere, and therefore can record everything without being detected (again, this is a simplified explanation).
You could also try using a different browser as well. I've seen several mentioned that can let you do things like circumvent the protection on OF and save images as you would with any other site, etc, so perhaps a combination of AZ and one of these "unlocked" browsers could do the trick?