No, it probably wouldn't work for plants in containers, but perhaps it would if the container were buried down to ground level.
When I say cut to ground level I mean right to the ground. An example of a plant to do that with is Salvia guaranitica. Another rule I follow is to not do it too soon, I put on the bags in December after the plants are dormant but the round hasn't frozen yet.
Yes, the bags sometimes do need to be held down so as not to be blown away by the wind.
I usually pull the bags off by about mid April here in zone 7a. If the plant is showing green growth I usually leave the bag nearby just in case there is more freezing weather.
The final use for the leaves is mulch. It is free other than the work it takes to bag them up.
