Hi Jenni,
Welcome. Looks like you got some good advice above. I too had similar situation as yours when I got my first Leopard.
I watched your video and it looks like the carapace is in good shape. Not sure about the plastron, but it should be on par with the carapace.
Did you mention how heavy your baby is in grams?
Even though you will need to make a few adjustments with your enclosure, I like the creativity.
One thing I wouldn't do is let the cat near the tortoise.
If it's more a worry about her (the cat) hurting him there's zero concern. She's like 14, loves everything, lets pet rodents climb and snuggle all over her, the parakeet etc. If it's for a health reason I'm curious to know, I definitely don't want him getting sick. This particular tort hasn't met the cat yet. We've only had him a few days.
I don't know how many grams he is, I suppose I'll have to get a scale. Where you able to watch the video? Does that seem really bad?