The original copy of the game came with a short VHS with live action video providing a bit of backstory. I wouldn't call it essential to the plot, but it's a nice little bonus. Any idea if this will be added at a later date?

Potentially but it would depend if the publisher and current rights holders even have the original recording.

The same was asked over at steam in October 2017 and Piko Interactive responded that they were in the process of converting it.

But they never added it to the Steam download. :/

Unfortunate.

wow, this is awful, I can't post links. Terrible forum. I would give you a link to the VHS video, but GOG sucks. Just look on the Steam forum.

Here you go, I think the dev from the Steam forum uploaded it.

Ability to post links is earned through reputation on these forums. It's done to avoid spamming and malicious links.
I'd suggest one of three approaches if you did want to share a link:

1. Be active on the forums in a way that is helpful and polite to earn reputation.
2. Share the link with someone who already has built reputation to allow them to check and post it.
3. Just copy and paste the url anyway, letting interested readers do the same.