Same, I guess it's time to go into Ultimate no spoiler mode!
Here's what I'd do:
1. Avoid basically everything that could spoil it. So don't use Social Media, even this site could be dangerous waters as the support thread for a character could change to say something like "WE DID IT".
2. If you can change Youtube to have Theater Mode when you boot it up try that. Thumbnails and video titles are almost guaranteed to spoil something.
3. If you can copy the stream link, try and put it on a document. Chances are the link will take you to the final uploaded version.
4. Enjoy!
5. (there is no step 5, unless you wish to share your reactions to the stuff included in the presentation)