M4V is a popular media format that's commonly used on Apple devices like iPhone, iPad, etc. M4V files are usually downloaded or acquired from the iTunes store and are DRM protected (Digital Right Management), hence you cannot transfer them to an Android mobile phone or another Mac. One app that can help you get rid of the aforementioned issue is Kigo M4V Converter for Mac.
This program communicates well with iTunes app and gives you access to a list with all M4V files purchased from the store. You can import as many videos as you like, choose from various output profiles, and even trim or resize the loaded clips.
Furthermore, the converter takes a small amount of time to offer you the quality results you need. Once the conversion process is complete, the app can automatically open the destination folder and you can play or share the videos.
Another aspect I like about this Mac program is that it features an integrated search tool (can be accessed after clicking the Add Movies button) which help you easily find the M4V files you wish to convert.
All in all, it's worth installing this app on your computer. The utility offers you many useful features, provides you with quality results, and comes with a fair price.