This video from the launch includes some footage from before liftoff were the pendulum has some momentum. I counted 8 periods over 10.2 seconds.
From that, we can find the length of the pendulum:
$$L = g\left(\frac{T}{2\pi}\right)^2$$
So
$$L \approx 40cm$$
51 seconds after launch, I can start to count again, giving 20 periods over 17.4 seconds.
$$g = \frac{L}{\left(\frac{T}{2\pi}\right)^2}$$
so
$$g \approx 21 m/s²$$
We have to subtract gravity, so the rocket is accelerating at a little more than $1.1g$.
At 1 minute 48 seconds (right before the escape tower goes), I can count 8 periods over 6.0 seconds. Using the same logic, that is about $1.85g$
Edit: I found another way to get a value for the acceleration: The camera angle in the beginning is constant, so we can use the time the rocket uses to accelerate its own height (45.6m). That is 4.9 seconds, so the initial acceleration is $0.39g$
At 2:57 a velocity indicator is visible, but that is cheating.
As experienced by the cosmonauts:
-1s: 1.0g
+2s: 1.4g
51s: 2.1g
108s: 2.85g