Watched this twice in 10 seconds. A T-34 (name withheld) shot down 2 planes, a 51 and D9 with one shot each. That's crazy.
The odds of a T-34 tank hitting an aircraft with its main gun were very low, especially if the aircraft was moving and flying at low altitude. It was possible, though, and a lucky hit could bring an aircraft down. 2 times in 10 seconds?
The T-34's main gun was designed to fight tanks, not aircraft. Depending on the version, it carried a 76.2 mm gun (T-34-76) or an 85 mm gun (T-34-85)
For a rough, illustrative estimate, a single shot at a moving aircraft in the very low single-digit percentages or below, depending heavily on the circumstances.
Just sayin