Every time I try to add a .mkv movie windows explorer stops working I was wondering whether there is a way to bypass it with another software like iTunes does for ios
Try rebooting your computer first. If that doesn't work, and if your computer and N7 are both on the same network, I'd recommend downloading the app called AirDroid. This is a free app.
AirDroid let's you wirelessly control your N7 or any Android device using the internet browser on your computer (your computer and N7 must be on the same network). It provides a very nice and simple interface on your computer that basically lets you operate your N7 from your computer, including allowing you to wirelessly transfer files between your computer and Nexus 7, meaning no USB cable is used. The advantage is that the interface for doing this is even easier than using Windows Explorer. The disadvantage is that the transfer is slower than connecting with a USB cable.