In terms of it veering to the left, everything I’m seeing there is normal. Single-engine prop planes simply do that due to three left-turning tendencies:
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Torque - the prop rotates clockwise, the rest of the plane attached to it wants to roll counterclockwise
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Spiraling slipstream - the air from the prop spirals around the aircraft, striking the left side of the tail, pushing it right and the nose left
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P-factor (or asymmetric blade loading) - the prop disk crates more thrust on the right side due to a larger angle of attack and relative forward speed on the descending side of the disk. This is more apparent at low speeds and high angles of attack, like during the initial climb
In a tailwheel aircraft (not here) you would also have gyroscopic precession. You also will get weathervaning effect, in which your nose will want to point into the wind. Finally, at low speeds, your controls will be less effective, giving you less ability to counter this until your speed increases.
But I believe the main problem is your controller. I see your controls deflect to correct and it’s almost a full, instantaneous deflection (then immediately neutral, then back again, etc). At speed, it’s almost not possible to do that in the real plane because of the airflow, as we said way upthread. A lot of folks here use yoke a or joysticks that provide artificial feel in the form of springs, but more importantly, have longer “throw” on each axis, so there’s a lot of nuance between a little and a lot of deflection.
That, and experience. 