I have been doing quite a lot of work with Drupal 7 the last couple of months. It has its ups and downs but one thing that it always tries to do is to prevent you from having to write your own code to solve problems.
It gets quite annoying then when simple things don’t work. In my case I wanted a content type with nothing but a title and a video field that shows Youtube videos that the editor pasted the URL to. That should work, right?
Then comes the kicker: without doing the following things didn’t work. The videos didn’t show up at all. It took me quite some time to figure this out.
At the Manage Display tab I had to first remove the video (make it Hidden) and then add it again so that I could choose a file view mode. See screenshot below.
The display types are defined in Config > File Types > Manage file display. Here I can choose Youtube video and after making sure the content type chooses a file view mode the video was displayed. *phew!*