No, it's not. Unless you do it like clipteez recoding the video with a watermark before downloading. Which is very annoying and makes the video quality bad but it's kinda save. But I've seen recent Blondie videos recoded with a grainy overlay to make it impossible to see the watermark anyway. I absolutely doubt that OF does any of this.
I dunno it's what she says.
"All videos are released in messages ONLY, and sent once. If you unsubscribe or get restricted and miss something, I do not resend videos ever. This is because messages are all sent out for purchase in batches, each batch is discreetly marked by me at a certain time in my video editor (final cut pro). This allows me to track leaks and figure out which group has a user leaking my content onto websites, assisting me with DMCA take downs while removing those who are pirating my content".
That'd be enough for me not to risk sharing them but I also have no intention of joining.