The parameter sublanguageid-all in an OpenSubtitles URL is a search feature that instructs the site to rather than filtering for a specific one .

sublanguageid-slo or sublanguageid-sk : Filters for Slovak subtitles (as seen in your snippet). Related Search Features

On , you will typically see this part of the URL change depending on your language selection:

The site uses several other URL-based features to refine searches:

: You can search by specific movie identifiers, such as idmovie-[ID] or idmovieimdb-[IMDB_ID] .