I would strongly consider supporting a video game union, if only to help formalize the things that the good shops do and bring those practices industry wide.
Personally I haven't done a day of overtime in seven years and I feel reasonably compensated but there are clearly other places out there that are still exploiting their workers.
Improving worker input into production schedules and creating clear guidelines around overtime compensation time would probably reduce companies that rely on "crunch time" too much. Over time is ok if the work needs to be done, but workers should have a reasonable expectation of knowing how much of a break they'll get after. Not that it's some random (small) number in their managers' head.
There are plenty of other workplace issues aside from over time and wages that a union could help address.
Increasing transparency and input from workers into company finances and road maps, improving hiring practices, creating more opportunities for young new grads to break in, increasing diversity.
Standardizing crediting would be one close to my heart.
One time I was laid off from a company along with hundreds others due to various company issues, and eventually the project I was working on made it to market. I made it into the credits, but instead of having a "software engineer" title and naming the significant feature area I worked on, I was reserved in a long list of "Special Thanks".
This sort of thing is totally unacceptable. Would be an area addressable by an industry union.