Wow, that looks like a lot of adorable energy
The fights mildly concern me but the playing sessions show some pretty good body language
. Lots of dogs are more "touchy" indoors while playing as there are some personal space issues that don't factor in as much when playing outdoors. I think that would sort out in the next while and the energy levels should also settle down a bit as well.
You also need to be honest and think if she is going to fit into your lifestyle and determine if you think you can handle all that energy. Does Molly have a good level of training? Will you have the time and energy to devote to the training that that energy level will probably require? Do you go a lot of places that you would take both dogs with you and if so will that be manageable. I must admit that personally I like my combo of one hyper dog and one older mellow dog
. I also often deal with my mom's dog which is my hyper dog's litter mate and it really is a lot of work but can also be a ton of fun sometimes
What a super tough decision for you
. I would definately give it a few more trys before making a decision. If it doesn't work then at least she got a good mental and fun break from the kennel and you will be able to provide the kennel with some more information on her mannerisms.