imho, you would have an easier time of it using video editing software. There's a lot of inexpensive programs to choose from that can do what you want. There's a learning curve, of course, but if you plan to do more videos, the time invested will pay for itself in the long run.
Ideally, you would want the GOK video ( found it here,
https://www.youtube.com/watch?v=XqLTe8h0-jo ) on your main track and then have the bits with your dog on an overlay track. Changing the audio levels will vary from program to program but they all have that ability.
Sony, Adobe, Pinnacle, and Corel, just to name a few, all have video editors at different price points.
Wait 24 hours before you decide. I'm sure someone will be along shortly with a different opinion or thoughts on the matter.
And it doesn't hurt to explore other options.
Joe
PS wow, Kitty is a little chatterbox, but sooooo cute.