As covered in mach's answer, this is a colloquial Swiss German greeting. Since there is no standardized written form of Swiss German, you may find it written in various different ways:
First word:
- Sälü
- Sali
- Salü
- Säli
- Sälüü
- Salut
Second word:
The host is mostly speaking Swiss Standard German, which is similar to Standard High German but with a slight Swiss accent and a slightly different vocabulary and grammar.
For the greeting, however, the host code-switches full-on into their regional Swiss German dialect, then immediately back to Swiss Standard German. It is quite common for professional speakers to inject some "color" into their speaking by switching to their native dialect or language for small interjections like greetings and farewells which are not relevant for understanding the topic they are talking about.
For example, a speaker from Texas may speak General American English, but greet the audience with "Howdy" instead of "Good evening" and address them with "y'all". A speaker from Hamburg may speak Standard German, but greet the audience with "Moin" instead of "Guten Abend". A speaker of Indian descent may speak in a generic English dialect, but greet the audience with "Namasté" instead of "Good evening".