There are at least two different camera bodies in your sequence of scenes.

• The one(s) in the first and last parts seem(s) to be an EOS 20D. There are enough noticeable differences to eliminate the 10D and 30D.
• The one shown at 0:31 and again at 0:43 is not a 20D nor any other Canon digital body produced by May of 2006. It is also not any Minolta, Pentax, Olympus, Panasonic, Fuji, nor Nikon digital SLR body that I can find released by May 2006. (Sony did not release the first α body until later in 2006). The appearance of the zoom scale on the LCD in Live View indicates it is probably a "bridge" type camera with a non-interchangeable zoom lens. By 0:49 in what appears to be the same scene as at 0:43, what looks like our 20D is back.

Back of Canon EOS 20D

There are also at least two different lenses in the montage:

• The lens shown at 0:06 and 0:014 is not an "L" series lens as a gold ring is visible near the front of the barrel. It looks to be an EF 50mm f/1.4 USM, EF 20mm f/2.8 USM, EF 28mm f/1.8 USM, EF-S 60mm f/2.8 Macro USM, EF 100mm f/2 USM, or EF 85mm f/1.8 USM (the last two are not likely due to how close the camera is to the subjects) with an aftermarket rubber lens hood attached via the filter threads. All of these lenses are very similar in size and appearance.
• The lens in the later sequences appears to be an EF 24-70mm f/2.8L

What about the speedlite and the lens with red hoop?

The external flash pictured near the end of the montage is not a Canon EOS flash.

Is it really an expensive L series lens or they simply borrowed one from an cinema camera that uses CN-E?

CN-E lenses would not mount on an EF camera body.

There is seemingly an first gen 5D by Canon.

None of the 5-series bodies, including the original EOS 5D, have pop-up flashes.