That looks honestly like faulty pressure on the machine. Did they use CO2 tanks back then or something else to get kegs to work? I imagine being in a wooden barrel as it appears that consistency wasn’t the greatest thing at the time.
That was a great video! Reminds me of being back in the UK, where real beer is still served.
@ Sean S. – Since that video is about ale, the system that the barman was using (and which is still used throughout the UK) is a pressure-based hand pump system. The barman is actually pumping the beer from the cask with every pull of handle. That overfoaming is caused from one of two problems – warm lines or an empty cask. When beer gets warm inside the lines running from the casks, it over foams when a pint is pulled. Likewise, when a cask nears the end, it starts to pull air into the line, which also results in an overly foamy pint.
About the wooden casks, they were just as consistent as the metal ones are today (from what I have been told by the old landlords that I knew). The real problem with the storage and handling of ale is that it is a living product with a short shelf life. When it is not handled and stored correctly, there are a number of things that can (and will) go wrong that will dramatically effect the pint that is pulled.