There are three things to consider. The first two are easy: who are you paying? why are you paying?
The third is a bit hard to explain but think of the need for a payment as a thing on its own distinct from the person you are paying and the reason you are paying. This often takes the form of a document like a bill or invoice but also could be more of an idea like a debt or a fee.
Who you are paying and the "need to pay" can be used without "for". In fancy words, they can be "direct objects" of "pay". The reason you are paying should be attached with "for".
"You pay the library."
The library is who you are giving money to.
"You pay for the library card."
The library card is why you are paying. You are not giving money to the little bit of plastic so you do not "pay" it and instead "pay for" it.
"You pay the library card fee."
The library card fee is the idea of needing to pay. You can think of it as a hole you need to fill with money into in order get the library card. Because the money is going into that hole, you "pay" it rather than "pay for" it.
If you appear and say "Hi, Bob the Canadian!" it sounds like you're saying hello to someone called Bob the Canadian. If you want to say hello and indicate that you are Bob the Canadian, then you need to say something else.
Saying "Hi, I'm Bob the Canadian!" implies that people don't know who you are - so it's fine in the first video but not in later videos.
"Hi, Bob the Canadian here!" is a way of announcing your presence, rather than saying your name. It's similar to when you walk into a room and say "Hi, I'm here!" or "Hi, it's me." But saying "It's me" is only suitable if you are very well known to the other person, not if you've just met a few times: it is polite for him to remind you of his name in case you've forgotten. If you met someone you'd only met a few times before, it's common to introduce yourself "Hi, I'm Dave, Susan's brother, you remember we met..."
It's common for TV personalities to say hello and introduce themselves in some way even if they're known, rather than just appear and immediately start saying "Today I'm going to be talking about..." It's perhaps politeness, as I said, and partly convention. It also give peoples a chance to pay attention, sit down, adjust the volume, and listen.
Best Answer
"agree to pay" would be a normal way of expressing this. (agree to pay in installments)
But it is grammatically valid to have "agree to (something)" For example
The structure here is "Agree + prepositional phrase"
A prepostional phrase can also be formed from "to(preposition) + gerund/participle phrase".
Gerunds are verbs ending in -ing.
However the meaning is pretty much the same as "agree + to-infinitive"