We can trace back Marek Ther’s first remarkable video experiments to 1998. In one of his first videos entitled "4:05" he first worked with his admiration for the opera diva Marie Callas. His fascination with this figure was later often interpreted in different ways. For instance, Zuzana Štefková interprets it as a game “of exciting ambiguity of relations between gender, sexual identity and sexuality, whereby the functionality of this self-staging is based on a paradoxical relationship between individual components of identity". Ther himself is more reserved towards these analyses; he understands the use of life models (besides Callas, Audrey Hepburn or Andy Warhol also appear in his videos) in the spirit of his "narration of a life record” via the medium of video as an integral part of the lived reality. Nevertheless the fact that in all cases it also concerns gay icons can loosely refer back to the very identity of he who chose these models.
Callas also appears in the videos What Gave Me America (1999), in his M.A. video My pleasure (2003) or in M. C. and A. H. (2001). His peak videos with openly homosexual themes were Hanes (2007) and I Will Get You Out and Chop You in the Midair (2007). In 2008, he began to work with different themes – the resettlement of Germans, the Sudetan-German culture, official Nazi components that he presented either as a fetishing of practices in imperial structures (Was für Material!, 2007) or in capturing the uncommonly emotionally dense, wholly concrete life moments that represented much more broadly the shared life stories given by historic reality (Pflaumen, 2011).
An important reflection of Ther’s work was the premature closing of his exhibition at the Prague City Gallery at the Old Town Hall due to “homosexual and Nazi propaganda”, in the word of curator Olga Malá. In 2011, Ther received the Jindřich Chalupecký Prize for his Das wandernde Sternlein (2011) video which tells the fabricated story of the disappearance of children in the 1930s in the border area. The video shocked with its natural aesthetic – it indirectly displayed a paedophilic act, but also contained a number of symbolic references and metaphors. The video was awarded by the jury above all because "beauty and horror, just as with mystery and rational, are presented in Ther’s work in complementary categories that are not mutually exclusive. The video also provoked negative reactions. A complaint was filed against DOX gallery for the distribution of child pornography.
He is presently preparing other videos whose footage is similar to that of feature films. He’d previously experimented with their external concise form in his short videos (for instance, they were all equipped with epic film subtitles that were often the same length as the film itself). Thus he strove to “grasp a specific story complexly, to create a record of life […], but so that it’s clear and comprehensible for the viewer”.