Obviously idea is cool. There could describe about forum rules and guidelines. But for regular update you need 3/4 additional staff. Another is who will own the channel ?

I don't know how many forum members will watch the channel. You can see on meta, how many people's are active here. To be honest 90% user are bounty hunters and they are busy with it. They don't have much time to perticipate forum discussion and I don't think so they will watch also channel. Increase new members means increase spammers by the way.

In my opinion motivate extisting users to avoid spam is more important rather than encourage more new people to join. Existing users also can be assets.

To be honest, I am agree with it to create YouTube channel. But in last few months there is lot of suggestion came out from members to build a decent forum. Especially add new moderators and recover accounts. Support existing users and reduce spammer is more important to encourage new user.