K, using some rough numbers:
This took about 0.7-0.8 of a second, by my admittedly fallible human ability to measure it. You gave a mass of 50 tons.
The block moved approx 1 meter. So, 1 meter in 0.7 seconds = 10 meters in 7 seconds. 10/7 = 1.42847 meters per second. so.. in our example he'd be unable to lift it over his head, but let's use the example where he threw a block up higher (1:09), and call it 2 meters. (hard to tell, the camera is behind Raziel.) This raises it to 2.85 meters per second. So, he'd be able to lift /about/ that much weight overhead.
Let's go ahead anyway:
If K = 1/2mv^2 then K = 184215.2012... joules. (lulz, 2012!)
Now, we know his joule output, K, so we can do...
m=2K/v^2
K = 184215.20126615
and v = 3 (what we decided a character coudl lift over their head.)
so m =:
40936.711392478 kilogram
90250.000000001 pound
40.936711392478 ton metric
45.125000000001 ton short
For Raziel to lift.