Exactly what you said...it would benefit him to have the lady do all of that for him, and he get away with not paying her. Lying, freeloading scum do things like that.
Back in the day, charging around 100 tokens per minute/1,000 tokens for a 10-minute custom video was the standard, which I and many other MFC models did. I think, since then, many models have decided to raise that to a higher rate. And even then, I've never heard of 1,000 tokens per minute for a custom video. That'd be $1,500 in your pocket, and that'd be phenomenal if it was real. Now I'm not saying there aren't some big spenders out there who would actually pay 1,000 tokens per minute for a 30-minute custom video. But you're talking about a guy you've never interacted with before on CB...who's never had a conversation with you before...and has never tipped you, right? He just randomly came into your room promising to give you an enormous tip like that after you send him the video first? Yeah, don't fall for that. Hell, even models' regulars wouldn't suggest shit like that.
The only time I'd say to go ahead and work on the video without first receiving the money...is if the site has the feature where the guy places a custom video order and pays the money...the model accepts the order...the site holds the money in escrow...the model completes the video and uploads it to the site...and then the site releases the money to you. Sites like IWantClips and ManyVids have this option. But you're probably not allowed to mention those sites while you're live on CB, or you'd get banned, right? So if you have a Twitter page, and this guy is smart...he'd go to your Twitter account to discuss it with you more there. Or he could just find you on the other site (IWC or MV) to discuss his custom video ideas there, and place his order there.