Do you mean play the movie on the TV (not read)? If the movie can be played in, say, QuickTime, and .mov's generally can, if not use vlc, then simply hook the TV to your iMac with appropriate adapters, fiddle a little with the Displays system preferences, and you are good to go.
In other words you play the movie on your computer -- it doesn't matter where the movie is kept on your system -- and view it on your TV or just your monitor if you don't want to connect the TV.
Update:
On rereading your post, where you used the word "read" and I interpreted that as "play", did you really mean "HDD" as a hard drive (usual meaning of "HDD") connected to your mac, or are you using "HDD" to mean something else too? My reply above interpreted that as a hard drive containing the movie mounted on your mac.
If this is some kind of multimedia player with it's own hard drive then I am not sure how you would play it on your mac. I would assume the player itself has its own video out connections (HDMI?) that you could connect directly to the TV. Mac is not involved.