Bit late to the thread here. That's the train régional, which I used to use all the time to get to Territet just by Montreux. Now I really avoid it like the plague, because I really hate the scummy people you get on it. I try to get the fast train to Montreux and take the bus to Territet. The régional has become dreadful. Watch your pockets and your back on that train. Over the last 12 years this train has transformed into something unrecognizable, like most of Switzerland has anyway.
I'm not talking about the kids that get on at Burier (from the gymnase de Burier), they're just kids/students and they can be boisterous, but are harmless.