.AVC? - AVC is code name for H.264, Its a codec. Where from you got it? From your HD Camera or from any Torrent?
Try to rename it to .MP4 or .AVI or .MOV and play... (Nero/Power DVD/Quicktime/FFDShow will play it)
Again .lst? Is it .LS(Lightscape) or .TS(MPEG-2/M2TS)?
.LST is a text file as per:
http://www.fileinfo.net/extension/lst
Can you try to open it in Wordpad? What's the size of the file? Can you post the headers of it?