Tiny white very hard cell bug! Please help to identify!
Definitely an arachnid and mite (subclass Acari), and very likely a member of the order Parasitiformes, of which there are more than 100,000 species!!

The body plan is not all too different from a tick (order Ixodida), but the movement of your specimen in the video doesn't seem to match that of typical tick. As such, I next began examining species in the related order Mesostigmata. 


Unfortunately, according to here, a clear detailed shot is needed to ID this specimen confidently:


  In most cases identification of Mesostigmata to family or lower can be accomplished only if the specimen is an adult female. The easiest way to determine the stage and sex of your specimen is to look at the intercoxal region.  Adult females have a genital opening that is almost invariably in the intercoxal region (species of Metagynella are exceptions) and covered by a sclerotized shield which may be truncate posteriorly or continue onto the ventral region.



However....

Mites just always seem to be associated with birds in urban homes, so I thought I'd do some google sleuthing....and voilà! I've found a near and reasonable match! 

Specifically, your specimen looks quite similar to mites in the genus Ornithonyssus of the parasitic family Macronyssidae -- these are bird mites (or possibly rat mites). According to here, 


  The tropical rat mite, Ornithonyssus bacoti, is one of the most common house invading species. The tropical fowl mite, Ornithonyssus bursa, and northern fowl mite, Ornithonyssus sylviarum, are also frequently encountered in homes. The latter two species are found principally on domestic or wild birds. The house mouse mite, Liponyssoides sanguineus, may also be found in structures with house mouse infestations. The tropical rat mite is a parasite on rats. Although none of these species are truly parasitic on humans, they bite people readily, often producing dermatitis and itching.


As for knowing the specific species, citybugs.tamu.edu suggests:


  Distinguishing between different species of Ornithonyssus mites to determine whether birds or rodents are the likely source is difficult and requires special expertise.


You can read more about Ornithonyssus bacoti, Ornithonyssus bursa, and Ornithonyssus sylviarum on Wikipedia, and you can see videos of these mites crawling on people here and here. 


According to here, Ornithonyssus bacoti can be found as far North as Iceland. 


 See below for images: 



 Rat mite (Ornithonyssus bacoti). &lt;1 mm;  © Erling Ólafsson; Source: www.ni.is  



 Ornithonyssus spp.; Copyright 2014 Tom Murray; Source: bugguide.net 

Note: I do not know this group of organisms well, so my answer serves as an (educated) guess to get you on the path toward proper identification...