Howdy John. Nope, I don't have sound in anything but it is possible. I do know that a TSUNAMI steam sound board will work with r/c, I have one and tried it in a Shay. I couldn't figure out how to access the bell & whistle but the chuff worked fine. I ran it for about 5 minutes to prove it would work...and went back to my prefered "silent running" attitude. I'm sure someone can answer your question, wait a bit.
I ran your video a couple of times without the sound on (not to alert the domestic management) or I get "No we don't have the room anymore"! But I risked it and she thought I was just listening to music. (Good idea that). I did pre-empt a little when you drove under the conveyer. (Will it load)? But all became apparent when you’re Lister? With three tubs came along, then your tipping mechanism. Fantastic.
You have the same tipping arrangement on the other loading chute. Do you use the same little industrial arrangement for that as well?
The build diary well thought out, easy to follow.
____________________ If it ain’t broke. Keep on fixing it till it is.