You might find that almost any video you didn't buy from iTunes isn't compatible with your iPhone.
To be more accurate, most videos aren't compatible with the video player app on iPhone and iPad.
That's why it's best to use a different video player, like VLC, which lets you watch almost any video in almost any format. You can download VLC here.
Check out the best, quickest, and easiest way to transfer any video from any computer onto any iOS device:
SEE ALSO: This brave movie shot entirely on an iPhone shows a raw side of LA
This is the screen you might get when you try to click and drag a movie onto your iPhone or iPad through iTunes. My videos are never compatible, like this video that's in the .MKV format.
To transfer that video onto your iPhone or iPad, download the "VLC" app from the App Store.
Then plug your iOS device into any computer with the video file you want to transfer, open iTunes, and click on the iPhone symbol.
See the rest of the story at Business Insider