hey y’all, hope you don’t mind me stepping in!
you’re both right :) a wagging tail means the cat is highly stimulated (think coiled spring, ready to go off). depending on the situation, this can be interpreted differently - just like people can smile nervously at job interviews vs. happily grin at friends.
in most cases, it’s safe to interpret overstimulation as ‘you’re doing something to amp up the cat & it wants you to stop’ (ex. unwanted petting). it should be seen as a warning; all that pent-up energy COULD be released as a swat or bite.
BUT in this case, that tail-wagging ‘frustration’ is the stimulation that comes from problem-solving (where can I jump? is it safe to go here?) and the excitement of play. it’s good to be wary of ‘cute’ animals vids, but this seems like an unproblematic video!