I was staying at a hotel for work recently where I got 1gb free wifi. I started watching Lightbox, and a bit over half way into a 40min show the wifi cut out - I had used all of my data. This surprised me, so I tested it a bit more using my phone's data (wifi tether) and sure enough a 40min show uses well over 1gb. This is pretty surprising and shocking to me - there are no quality settings so you cannot change it, and this seems like extraordinary data usage for a video streaming service in 2016.
Worth being aware that Lightbox is very data hungry, even for a video streaming service.