I think we need to distinguish between different goals here.
If muscle mass in general is what you want to maximize, compound exercises help you work as many muscles as possible with a single exercise. This is why they are recommended: Most people want to build all their muscles, not just one or two in particular.
If biceps mass is what you want, and you are not interested in anything else, then I'd agree that you may as well do barbell curls, or other isolated biceps exercises, and those may be more effective for your particular goal.
I don't think it's credible to suggest that compound exercises are better if you simply want a huge biceps; it's just that most people want more than that. Some people (perhaps the guys in the video) may think that compound exercises are better no matter what, but that's not true. When experts recommend compound exercises, there's an implicit assumption that huge arms are not your only goal.
Also, most would argue that compound exercises are not necessarily more effective, they are more efficient. They allow you to work out lots of muscles in a fairly short amount of time, while isolated exercises will take a lot more time for a similar effect (to have all muscles covered). Of course this is irrelevant if you only want to work one particular muscle.
Other benefits of compound exercises include:
- They place greater demands on your cardiovascular system, improving your aerobic strength, heart muscle function, and blood circulation.
- They train things like coordination, reaction time, balance.
- They enable your muscles to grow in the right relative proportions; with isolated exercises you run the risk of neglecting certain muscles that are important for real-world activities.