Aeration & mold

With warm weather here, I wondering about aeration techniques to avoid mold.
We've been pouring the wort back and forth between two buckets, (how much is too much?) and have been brewing in my garage with the doors open.
Also, I just watched a video online where the guys just poured the cooled wort into the fermenter bucket, put his thumb over the airlock hole, and shook.

Does the wort get enough o2 that way?

Questions about mold;

If the o2 answer is yes, wouldn't this be a safer way to aerate?

How much of a mold danger is there really? (I live out in the country, way out...)

Should I be brewing in a closed room?

I hit the headspace of my carboy with a can of O2 for about 5 seconds and then shake for about a minute. If you don't want to use your thumb, you can always get a solid rubber stopper.

I have never heard of mold being a concern for anyone. As long as your equipment is sterile, and so is the wort and you are not sweating into the bucket then don't worry. Get the wort to correct temp asap, stir like crazy, and then add the yeast when it stops spinning.

I find it interesting that many people make a big deal about getting oxygen into the wort. Using a normal plastic spoon for a 23L batch in a 50L or bigger bucket you can do fine. There is a certain "finesse" you get after several batches by holding the spoon properly by rotating the top part of the handle rapidly, while keeping your other hand a foot down in a stationary position. This makes an incredibly strong whirlpool where the "whoosh" noise of the wort will let you know you blended lots of air in real quick. Actually I was very surprised the first time I stirred correctly - the results are obvious. It will suddenly appear as if you have an extra gallon or 2 in the fermentor, as the air is so mixed in but invisible.

I have no idea how people do it when fermenting in carboys or same size containers.

With beers with a lower SG I just eithers shake it or make sure it flows sporadically through the funnel to incorporate oxygen.. Beers over say 1.06 I use a diffuser stone and oxygen tank.
If you are shaking it with your hand on the end of the carboy, be darn sure you've soaked your hands in sanitizer or you'll risk infection.