I watched the first third of your run, then rushed through it for a bit less detailed insight.

Overall your healing with AST is pretty solid.
You kept regen on the tank, used your cards on the right party member, or for the whole party when you got an arrow or balance.
(Except this one time you used it on yourself.) :P
This tank didn't seem to use CDs often...
I wouldn't say the run was rushed, but the tank definitly didn't help making it much easier for you.

You draw cards almost constantly. Try to keep it more on CD, and draw that monster... eh, balance card!
(For optimisation): Don't "Draw -> Royal Road -> Use" in a row, use every step between your GCD or use Combust to double weave.
The recent balance changes to AST allow you do that without clipping your GCD.
Also, you can use Combust on big adds, after 4 ticks (12 sec) it's more damage than Malefic I, and big adds live longer.

You can hold Essential Dignity until your tank drops 20-30% HP. Essential Dignity is your Benediction 2.0 on 40 sec CD, treat it as that. The less HP your target has the more it heals.
It's specifically strong in (low) leveling dungeons. (You can "bene" someone with Essential Dignity if it's going to crit.)

But one thing I noticed: You never used Lightspeed! I dunno why you kept it untouched. This ability makes every cast instant (except Ascend) and cuts your mana cost in half.
If you need to move, or need an instant heal while Essential Dignity is on CD, use this. Or use it whenever it's available, just use it.

(You don't need to heal the flame breath from the dragons in the first part of the dungeon, you and your mates will regenerate it over time, just focus on tank.)

On a side note: Do you always play with your camera so close to your char? Do you not want to zoom out further?
I had a lil' trouble keeping my overview in this. Especially when you stand behind a boss and they show you their big "yo mamma"'s butt.

Well, that was a lot of nitpicking and more than I intended. Overall you are "getting the hang of this".
(Don't take anything in this post too hard, I am just a nitpicker. ¯\_(ツ)_/¯ )