I bought a few of her OnlyFans vids ($10-$25 ea), and requested a private video of her busting a shirt's buttons, then softly masturbating ($500). Being my first OF membership, I was more than surprised how much & quickly I was belting out that kind of cash. What's worse, I can't save any of the vids I bought to see.
Then you should seriously consider installing a screen recorder, start recording just short before watching the video and ending recording afterwards. Then perhaps cut the start and end afterwards. But this really sounds like a shame. Or try a link extractor for downloading linked media like JDownloader 2 which is way more comfortable than screen recording if it works.
If you are using a computer that runs the Mac OS X operating system you have a built-in screen recorder for free: QuickTime Player. The audio may be slightly muffled and/or echo-ey (since it's not getting the audio straight from the input but is recording the audio that comes out of the speakers) but it will work.
If you use Google Chrome to view the video from OF, you may be able to use the free Chrome Extension Fireflies to record the video and audio. I haven't tried it yet but I hear good things about it.
Or you can use screen recorders like Loom, SnagIt Recorder or Camtasia. They're not free, but they work well.
On Firefox, I use an add-on called Video DownloadHelper that does a pretty good job on all the sites I use.
Sorry for the reply to an old post. As long as I have OF, I can watch the video whenever I wish. Still works after several months, but I've never been any good judge of PC apps. I have a YouTube downloader, and even purchased the 'elite' version or whatever, and still can't DL vids.