A quick question - how do I get refunds for games that I no longer want? I had purchased a few games off of GOG but found later on that I actually have physical copies of then. And what is the cut-off point between being eligible for a refund and not being eligible?

The cut-off is 30 days after purchase.

All about refunds: https://support.gog.com/hc/en-us/articles/360011314978-How-do-I-refund-a-game-?product=gog

Thirty days from the date of watching the VHS imean the purchase.

In most cases, you have 30 days to request a refund. The specific policies are on the Support site:
https://support.gog.com/hc/en-us?product=gog&_ga=2.30420287.1456229756.1609206423-1668724065.1601769128

Note that the 30 days applies to the date you submit your refund request. So if you submit a ticket 20 days after purchasing a game, but GOG takes several weeks to reply and complete the request (which is definitely possible now, since they are SEVERELY overloaded with support requests) then you're still good because your initial request was within the 30 days.

On a similar note, if GOG takes more than 6 business days to reply to your ticket - DO NOT open a new ticket. Reply to the existing ticket and/or send a personal message to one of the moderators here on the forums, asking them to look into why your ticket hasn't received a response.

on current average Gog will take 2 weeks to reply and the reply you get will be the auto- "we got your message but don't really care" they send out to everyone... you have to then send replies to that email in order to get any closer and these replies currently take about 4 weeks each so you can expect to get the money back in about 6-8 weeks after you first open a ticket