I met Jenith back in the days when I played a lot of DDR. He was good in both technicalities (passing very difficult songs) and styles. Being an amateur, I always applauded after his "performance", and he would bow a little bit with a smile :) on his face.
When I went back to Hong Kong some years ago, I saw a great play of DDR by a guy in some arcade. As usual, I applauded after his performance and, suddenly, I felt that many people were staring at me. The crowd (including the guy I applauded for) made me feel that I just did something inappropriate (singing in the public?) and I stopped clapping and silently left the arcade. (Dang, I must look like some kind of bozo)
From these two events, you can see one big differences between the US and Chinese cultures. Chinese, in general, are pretty stingy of praises. I don't recall my parents or teachers ever taught me not to praise others in public but for some reason most Chinese just won't do that.
"Well, we applaud at real performances like concerts," you said.
No, you do that because everyone else is clapping. Will you stand up and clap when most of the audience think that the performance sucks?
Anyways, I think that there's nothing wrong in praising others when you truly think that they do a great job. A praise may be just a few words to you but it can be a sweet memory to the praised one for a long time :)