EF-M to EF adapter on EOS M6 ii loose. 70-200 can fall off. What can I do?

As usual - excellent advice and photographs. 

Marco Nero wrote:

The Original EOS M body shipped with the Lens Adatper in the box - in an attempt by Canon to sell the EOS M as a "backup camera" for professional DSLR shooters. You can see it on the side of the box in this image from 2012.

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You asked "what can (you) do" and there's literally but one answer: Get your hands on a genuine Canon lens adapter. There's simply no alternative...
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The Viltrox adapters & devices are well known to be horridly loose-fitting. I had a Viltrox tele-tube (not the Lens Adapter) detach with an EF 100mm Macro lens attached to it when I was shooting Macro images with an indoor lighting setup ... almost ruining the lens when it struck the glass table. I was picking the camera up and it literally fell off, even though I'd locked it into place. It was as though I'd pressed the lens-release button. I will not use their products any more. The worst offenders are their EF-to-EF-M adapters. There's plenty of stories about them online producing loosely fitting lenses with poor electrical contacts and a penchant for detaching with larger lenses. You can see just some of the lenses I've adapted to my EOS M + EOS M6 cameras directly below. The snug fit is important.
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EOS M6 + Canon adapter + EF 100-400mmL II lens

EOS M + Canon Adapter + EF 24mm f/1.4L II USM lens

EOS M + Canon Adapter + EF 50mm f/1.2L USM lens

EOS M + Canon Adapter + EF 100mm f/2.8L USM lens

EOS M6 + Canon Adapter + EF 85mm f/1.2L II USM lens

EOS M6 + Canon Adapter + EF 100-400mmL II lens (with other accessories).

EOS M6 + Canon Adapter + EF 2x III Extender + EF 100-400mmL II lens.

EOS M6 + Canon Adapter + EF 1.4x III Extender + T-Ring + Celestron Mak90 Spotting Scope

EOS M6 + Canon Adapter + EF 1.4x III Extender + T-Ring + Celestron Mak90 Spotting Scope

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Toss these Viltrox parts into the trash and replace them with a genuine Canon lens adapter. The difference will be night-and-day by comparison. I still use the original Canon adapter that came with my EOS M body (Canon used to supply it in the box back in 2012) and here we are 9 years later and it's on my EOS M6 when needed. It's still tight to get it to connect to the camera EF-M lens mount. These Canon adapters are built tough and will prevent the type of movement shown in your video.
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There are TWO versions of the Canon Lens Adapter... one has the "foot" included. This can be VERY handy when mounting larger lenses that have no lens ring with their own foot. The other has no "foot" included. The foot is removable (see image below for reference). And even if you remove the foot to enable various lenses to be fitted without interference, there's yet another tripod-mount on the underside that the "foot" screws into. I've found the foot useful for mounting a Manfrotto mini-tripod to (see below). Because larger lenses can sometimes prove tricky to carry. So with the lens foot attached to the Adapter, there's very litter pressure on the camera mount ring and the lens itself is snugly attached... thus relieving any pressure from the camera mount. I can walk kilometers holding the rig (below) without much stress on my hand or camera mount. Both the EOS M and the EOS M6 can be seen below with my favorite EF lens combo on the Lens Adapter...
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Making use of the Lens Foot that came with my Lens Adapter... by fitting a mini Manfrotto foldup "tripod" solely for the purpose of carrying the camera more securely.

Accessing the M6 battery with the Mini Tripod attached to the Adapter's lens foot.

Top View of the above array.

Stable on a table 1

Stable on a table 2

Canon EF-to-EF-M Lens Adapter with "foot" attached. Canon appear to supply two versions... one with and one without the lens "foot". It is made from metal and has a tripod mounting socket attached.