Balance is a big deal to me as I have some bones loss. I use most of the above mentioned videos.
It is good to vary balance work on stable surfaces and unstable.
An important factor in balance is ankle strength and mobility. Any exercises to improve these will help. Tight calves can also affect balance. I like to use a foam roller (or any other myo-fascial self-release tool) to loosen my calf muscles.
The original
Wii Fit has some fantastic balance tests and games to improve balance and coordination on the Wii Fit board. (I don't know if they even sell these anymore!)
The biggest factors for increasing balance are consistency and frequency. I work on my balance here and there
every day. In the evening, DH and I play Wii Bowling for 30 - 45 minutes. I practice standing on on leg, I do moves I've seen in balance videos, and I just generally goof around testing my balance.
Thankfully, the DH finds this amusing.