VIDEO/AVI QUERY. I HAVE D/LOADED AN AVI OF 741Mb ?

Got the file from Bearshare...I HAVE D/LOADED AN AVI OF 741Mb and in explorer the runtime is only 3 minutes - why is this?? Has some freak been messing with the video file to waste peoples time or is it a d/load error? Took me about 8 hrs at my speed!!