How to transfer my videos from my iphone to my computer and be able to play it?

I have a lot of video on my phone and it is taking up to much data, so i want to transfer it to my computer so i can have more room for music. I tried transfer it and got some on my computer but when i try playing them the computer says that windows media play can't play this file because of something. How can i do this please someone help. Also i looked up videos on youtube and they do not help

Buy a USB charger and put the USB into your Mac or windows computer and start syncing.

You need to install quicktime player. Quicktime can play iphone videos.
Now, To import your videos Videos From iphone to PC,
1- Connect your iphone, A dialog box will appear, you will see option to "Import Pictures & Videos" in there.
2- Click that and make your selection of pictures and videos to import.