I think the best thing to link up the expo booths and the expo-booth live-sessions is to simply add the expo booth live session video to the top of the expo booth page when they are live, and have all of the other expo booth stuff below it.(description, links etc)
This would consolidate the two chat rooms, and make the expo booths more interactive and easier for people to see special offers, and click through etc.
It would also be easier to get people to the session from the schedule link.
Or you could:
1) When there is a live session in the expo booth then redirect new people entering the booth to the live session automatically.
2) Display a video preview of the live session gif of the content being shared where the join button currently is - with a live icon - to make it more obvious that it is live.
3) Allow the schedule link to point directly to the live session and not just the expo booth.
4) When inside a live session in the expo booth, then display all the booth info below the live session video. (description, links etc)