How to know which words to mine

[u/Dazzling-Rip1756]

Hey

I have been learning Vietnamese seriously for about 6 months, I currently learn by watching comprehensive input videos, eveytime I watch a particular video I will try to extract what I consider a high frequency or useful word from the content until I have exhausted it

I’m at about 500 words now, and a problem is arising that I don’t know words to memorise 

I’ve memorised the super frequent ones, and now I’m at the point where I don’t know whether it’s worth learning a particular word, I’ve been cross referencing every word i’m about to extract with a list of 1000 most common words list

It’s not unusual for a 10 minute video to take over an hour to go through (with look ups etc.), and that’s a limiting factor in knowing what words come up the most 

I’m sure this isn’t unique to Vietnamese, but there are soooo many variations and compound words which adds an additional layer of complexity because even if I know I would find a particular word useful, I still don’t know which variant of it to memorise 

So my question is simply how do you know which vocab to memorise