I purchased an August VGB100 USB capture stick off of Amazon, after not having any luck with an eBay C-DVR, and not wanting to spend over $100 on a better quality standalone DVR.
Amazon.ca ($25 Prime): http://www.amazon.ca/gp/product/B008F0SARC?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
Amazon.com ($17 Prime) : http://www.amazon.com/August-VGB100-Video-Capture-Device/dp/B008F0SARC/ref=sr_1_1?ie=UTF8&qid=1441950039&sr=8-1&keywords=august+vgb100
August site: http://www.augustint.com/en/productmsg-90-124.html
Because I have a Surface Pro I didn't have a huge portability barrier to overcome, but anyone with a laptop could easily transport it to wherever they are going to fly:
I've seen many "EZcap" sticks on eBay which run around $15, but they all have terrible ratings, terrible software/driver support, and many are fakes which wont work at all. I've never heard of August but for $30 I figured it was worth the chance.
The software (ArcSoft Showbiz), is basically a typical basic video editor/converter, but it has tab devoted just to capture and there's not much that needs to be done to get it working.
If you want easy, no-fuss FPV cam video to overlay atop a GoPro vid, you can't go wrong with this thing for the price.