If I was given the opportunity to prepare for a Vogon invasion, in the terms of the original post, I would obtain a portable DVD player with USB connectivity, and the highest capacity portable hard drive to couple to it. So that taking a large quantity of video footage would simply be a matter of picking up the rucksack and making my escape. Power banks and mains adapters would be included.
I would concur with the idea of taking a full set of Attenborough documentaries, as a memorial for the now doomed Earth, as well as for educational value and unrivalled natural spectacle.
As for movies … hmm. Don’t have a big list of these, but two standouts are:
The Hunt for Red October … I’ve always pictured myself as a Captain Remius figure, preferring strategic planning to being caught on the hop.
Heavenly Creatures … an early outing for Kate Winslet, as one of two young schoolgirls who gravitated into each others’ orbit, entering an ever tightening spiral of obsession. Which led to the real schoolgirls in question becoming embroiled in a particularly grisly New Zealand murder case, with some interesting fallout.
I’d also include The Internecine Project starring James Coburn, a thriller made in the days when Hollywood still aimed to appeal to intelligent adult audiences. I recommend this to anyone who hasn’t seen it.
Blade Runner (the original) would also figure, because Rutger Hauer’s “Tears in Rain” soliloquy is one of the finest pieces of cinema of all time.
Finally, The Expanse sci-fi series has to be included. Billed as the most realistic sci-fi series thus far produced. “This is the warship Rocinante” happens to be my ringtone. 
As for most of the Hollywood dross, in the words of David Hume, “commit it to the flames”.
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