No problem. I have now watched your last Elizabeth video and the first 2 Byz videos. I enjoy your commentary and think you will quickly get very good at this game. Now to my thoughts:
Elizabeth: Okay, so you went for a domination victory and actually got Moscow. Great job! But you got stuck at Gao and were eventually broken... why?
The answer is simple: growth. You didn't prioritize growth. Look at your capitol: 8 pop. Now look at Gao: 16. Even St. Petersburg had 11. Growth is critical because more pop = more tiles worked, and even better, more science. Your science at T219 was 60... it should have been about 4x that, or more. You were just starting to build a university in London...way too late. Did you build the National College?
You got behind on science, then tried for an ill-fated attack against Gao with a few pikes, catapults and a trireme... there was nowhere for the catapults to set up to fire on Tombuctu (even if they had gotten close enough to the city), the lead pike was left out in the open and even if you had wiped his army and taken Tombuctu (22 defense), Gao had a
36 city defense... so how high was the attack of your best unit? 13?
And across the world Catherine attacks you with Longswordsman and Crossbows, which are medieval/renaissance units. You're defending with... spearmen and an archer, ancient units... she's 2-3 eras ahead....

ahem, science.
Byz: I like your initial thinking here. You want to found a religion: great initial strategy for Byz. So here's my thought about the rest of your strategy:
Victory condition. You comment you will probably go for a "cultural or science" victory. Byz can do either, but each requires an entirely different kind of play. They are opposite victory types. Think about the social policies: piety and rationalism. You can't have both. Some victory conditions can be switched to others (science start, then domination, for example), but not these two.
Opening. You opened with a monument. I normally build a scout -> worker, but that's okay. You got your worker from Liberty... why did you pick Liberty? Liberty is for founding lots of cities... were you going to do that? Probably not for a cultural victory, maybe for a science victory though. Still, you need to found 5+ cities for Liberty to be a better choice than tradition. Liberty can also be good for Byz to found a bunch of cities with Shrines/Temples for faith. Were you planning on doing that?
Tech. Pottery was an excellent first choice. From there, you should have gone Calendar, then Sailing (develop luxuries, sell exess to Dido!). You went mining...

your worker came out, again, with nothing to do.
Religion. This map was a great start for Byz. I hope you took Desert Folklore as your pantheon.
You are doing better. Keep it up!