Use these special links from Cut/daily's current sponsor, and you shall have your wish!
When I used to edit with clients in the room, or have people come in for an attended review session (remember those?), right before hitting play it would be easy to turn to everyone and say:
"Right now the graphics are still temp..."
"This isn't graded yet."
Or all manner of little notes and reminders to help frame what they're about to see.
These days I try to list these things in the email that contains the link to Frame.io for them to review, but you never know if they're really paying attention until you get comments about the stuff you already mentioned in the notes they ignored.
A better way is to add a front slate to the file you upload which once again reminds them of the current condition of what they're about to watch.
Among other things, this helps to head off some notes at the pass ("The images look a little washed out... - Yeah, it's not graded yet.") and also to ensure they're watching the correct version etc.
The History of Broadcast Video Tape Countdowns
These kinds of front slates/count down clocks originated from the days of delivering tapes to for broadcast, so that they knew what the show was and could be cued up to start at the right time.
These slates also included a fair amount of technical details about what each audio track contained, video resolution, the run time of the show etc.
Video must not contain color bars, bumpers, segment recaps or previews, advertisements, slates, ratings cards, FBI warning cards, VITC time code, placards, overlay branding or website link callouts before, during and/or after the program. URLs present during end credits are permissible.
— Netflix Delivery Spec
Today they would only get in the way, and in fact, as per Netflix's delivery spec all they want is 1 second of black at the top and tail of the show.
But something like them is still useful for keeping those clients in line.
The Future - My Frame.io Feature Request
What I'd love is if Frame.io were to build a slate feature into their video review service whereby you could create a front slate - either as the holding still of the review file when the review page is loaded, or as a few seconds of branded count-down leader.
The benefit of this is that you could list all the details you wanted by filling in a few text fields AND the slate isn't actually part of the uploaded file (it's just some web magic) so the client can still download it and use the file, as is, without having to remove the slate, or for you to re-upload the file without the slate.
Please and thank you.