Even our own Physics Teachers SOS (PTSOS) workshops have demonstrated this and had mixed results.
For several years I did not have a set up in my classroom that I felt was safe enough for this demo. I found this clip from Brainiacs a suitable replacement for a long time:
I especially like the fact that they try to adjust for the loss of energy (great discussion of work) in a secondary experiment. Of course doing it yourself is always best, but if you can't, this is my favorite replacement.
After I made my new pendulum (more about that here), I was able to make some new videos. My English teacher neighbor was kind enough to assist. Although I should have given him some more initial instructions.
In case they don't think its a big deal, here's a point of view version:
There are many, many more out there if one of these doesn't fit the bill for you!