In a number of the worlds in which I'm involved, it's fairly common to hear the assertion that lifting weights fast is all you need for cardiovascular training.
Enter the kettlebell, the tool that allegedly does it all.
I've even been asked whether it's possible to train for a marathon using only a kettlebell. The answer is "no".
[Even if the answer was "yes", why would you want to run a marathon if you hated the idea of running enough to be able to run a marathon? But that's another topic altogether.]
The first reason why lifting weights fast is not great basic cardio is that it is interval training. The intensity is simply far too high on the work parts and too low on the recovery parts.
I mentioned in the video that I've never seen anyone who is able to do properly executed kettlebell swings at a low enough intensity to do so for a continuous 30 minutes or more.
The second reason is because of the nature of breathing used during ballistic weight lifting, which causes something called left ventricular hypertrophy.
Left ventricular hypertrophy is enlargement and thickening (hypertrophy) of the walls of your heart's main pumping chamber (left ventricle). The thickened heart wall loses elasticity, leading to increased pressure to allow the heart to fill its pumping chamber to send blood to the rest of the body. Eventually, the heart may fail to pump with as much force as needed.
To use the kettlebell swing as the example again (because it's the most common "lifting fast" modality), you should use a bio-mechanical breathing match, including a brief breath hold and whole body tensing at the top of every swing.
This breathing pattern causes compression of the tissues around the blood vessels, delaying the return of de-oxygenated blood to the heart. The result is a small volume of blood being pumped out to the body by the left ventricle. In order to pump hard enough, the left ventricle has to contract more than usual.
Over time, the walls of that chamber get thicker & the left ventricle gets smaller. This results in a heart which is (a) stiffer & (b) able to pump less blood per beat, the opposite of what we want from cardiovascular training: A flexible heart with large chambers.
For the occasional workout or if you're training for a Strongfirst or RKC Kettlebell certification, swings are great (I love doing swings, myself) but they're not a good option for health-based cardio.