Those links say "instant download" so if it isnt an outright scam, it would shirley have to be eticket.
Any Brighton fans would have their name and membership number on it so you'd have to be a prize fool to sell that to a stranger.
As its the Europa League game, maybe a % are given to Uefa...
Dunno about stubhub but I've been forced a couple of times to use alternative well known resale sites (not for footie) and they have gaurantees usually or insurance against such, for couple of quid.
How is this possible for Albion home games with rules about passing on tickets?
Surprised the club don't buy a couple and very publicly ban those behind the illicit sales?