There is no direct way to remove DRM protection on iTunes M4V videos by yourself, since you are not the professional one in this field. The only way for you is to discover a smart third-party software. Suggestion about DRM removal tool as below:
The best free iTunes DRM removal tool could be Requiem, but it may not work in some computers with the new iTunes version 10.8 or above directly. I would not advise to downgrade the operating systems and iTunes versions.
Luickly, there is an alternative to Requiem, called DRmare
iTunes DRM movie converter, which can remove DRM and convert iTuens M4V to WMV and other common formats. So you can play iTunes movies on Windows Media Player without any limitation.