I'm sorry, I certainly didn't mean to say you purposely take credit for the encoding. I noticed you often write that you take your files off Winny. It's just that by adding your nickname to the file it creates confusion for some.
I also didn't say that what other bittorrent sites do is 'correct'. I also think they should leave the filenames as they are.
In regards to the 'trip' on Winny, I asked a friend of mine who's often on Japanese P2P and related message boards and he says that their trip (I think it's called like that) is the equivalent to a nickname, the same as PDD or Alf17 are not our real names but a unique identifier. Apparently, a trip is unique to a single user.
The files I get from my friend usually include the original file name and trip of the encoder, which prevents confusion as to the quality and origin of the file. I think he sometimes uploads files to share with others as well and a way to prevent others from 'stealing' your link is to put the .avi in a zip or rar file and password protect it by something like Uploaded_by_PDD. In that way you protect your upload while at the same time keeping the information regarding the encode.
But in the end it's up to you to decide how you go about it.