I'm not totally familiar with the rules in Canada (I think you're from Canada), if they're different, but reaction videos are fine to make and you don't owe the original creator money, as long as it falls under fair use.
Now, fair use is a tricky thing, you have to fall into their specified set of rules, which basically means it has to be transformative in nature. You can't just play a video or movie with your face in the corner and call it a reaction. You have to have commentary, critique, parody, something that makes it 'new' content. It's also considered polite to give credit and put the links to the original in the description.
Now, whoever or whatever you're reacting to might not understand fair use themselves, especially if it's more like criticism.
Please, please, please, read YouTube's info on this first though. I am not sure, but I think reactions cannot be monetized, and can even get a channel completely demonetized if you do them often. I don't know if this applies outside of the United States, so please double check for your country and region, if applicable.
I'm not an expert, but I didn't want to leave you without an
answer or a place to start double checking your specific needs.
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