The high amount of calcium in milk more than makes up for the loss of calcium that comes from the protien in it.
You experience a much greater loss of calcium, to the point that it is a danger to bone density, only if you consume large amounts of protien via meat products, that don't contain as much calcium as milk, AND don't drink tons of milk to make up for it, which most adults here in the US do not. Heck, kids don't even drink milk as much anymore.
Yes, you can also avoid consuming both altogether by eating tons and tons of vegetables as well, but the amount needed to make up for the lack of calcium ingestion that you would gain from a simple two glasses of milk is astronomical in comparision, which most, if any Americans, do not either, at least on a daily basis, unless they do actually eat 40 servings of broccoli or 250 oranges every day. Especially kids, where calcium is most important to their growing bones.
Besides, the person who made the video doesn't consider any other factors as well that would be in play for the fact that different ethnicities have different prevalence rates of osteoporosis, especially ones that line up the differences better, only jumping on the chance to use it as to proof that consumption of dairy products is not beneficial to its prevention.
I saw studies that found out that asians have almost the same rates as caucasians and that blacks and hispanics are much further below, which DOESN'T line up nicely with video's theory of animal diet being the primary cause of higher rates, does it?
I saw some studies pointed out to the prevalence of smaller bone structure in certain races as one factor.
I saw others that point out to obesity and its toll on bones, others to a specific combination of certain bone structure mass and body weight.
And almost all studies that tested a lack of calcium in diets came away with conclusions supporting its intake, especially in childhood, when bones are still growing.
Those that have done comprehensive peer-reviews of these studies have concluded that it is bone genetics that is the primary factor, followed by a lack of calcium in childhood, followed by a lack of calcium in adulthood.