I wouldn't call myself an experienced FPV Pilot but I may as well give my thoughts anyways...
As far as I can tell these should work with a separate video receiver, as they have an AV input port, this dukes mean however that you will need to build a ground station to house your FPV receiver and the batteries that power it. For this application it wouldn't be to big, but you will still be carrying around something a lot larger that the goggles from Fatshark, etc. By going down this route you would be loosing the lovely compact design of goggles that have everything built in. So setup at the flying field may take longer and be much more hassle than the Fatshark goggles, etc.
Then there is the main issue I can see, from what it looks like these goggles have no eye cups or other attachment to block out the sunlight. This is not a fault with the design, as FPV may not have been the thing in mind when these were designed. This may cause you problems on a sunny day, as you may not be able to see the screen due to the reflection of the sunlight.
Also I cannot say for certain but if you wanted to upgrade to an OSD or even when just flying bare FPV, you may not be able to see the little details. This may not seem so bad but trust me, those posts and poles are like magnets and if your goggles don't show good enough detail you probably won't see it until it is too late.
Then finally, there is the price. At $399.99 or more for a good pair, you may as well buy some proper FPV goggles. As at that price you would be getting so much more "bang for the buck" and you would have something that would grow with you into things like head tracking with pan and tilt (with the attitude SD goggles for example, the ones that Flitetest use).
I know this is long but I want to make sure I help you the best I can!
My honest opinion?
Buy a good pair of dedicated FPV goggles and get a portable media player or download videos onto a tablet or notebook you may have. In the long run this will probably be much more cost effective.
However this is just my opinion, don't take it as law and get some other peoples as well.