Talk

I'm looking for a DVD or tablet to attach to the headrest of the seat to try to keep DC occupied for a 6 hour car journey. I've seen kids with them in cars on the motorway but I've never seen them in the shops. Can anyone recommend one? I thought maybe a cheap tablet but can u download films onto them? Iplayer etc wouldn't be suitable because it could stop while we're on the motorway (imagine the drama that would kick off!). any ideas?! Also do they come with something to attach it to the headrest or do I need to buy that separately? Thanks!!