Altschwedisch, versteht ihr Isländer es?

This looks far more familiar than modern Swedish, yeah. I would say about half the sentences there or maybe a little less are completely comprehensible.

Most of the rest *almost* are. There’s just enough unfamiliar keywords in a lot of these sentences to scramble them for me, even though most of the words are obvious. Like, I didn’t catch that „fiæt“ is the noun-form of „feta“ until the guy in the video explained it.

Edit: are you the guy? I’ve seen some of your videos before.

It’s almost as his thick swedish accent is making it worse. I understand more from reading the thing rather than listening to the swedish guy. Many of the words are the same as in current Icelandic. Not written the same but spoken the same. While we understand many of the words it’s still down to the dialect which is really old, not even old folks in Iceland speak in such sentences. If an Icelander would read this out loud I reckon it would be much easier to follow. The Icelandic language is the closest to the language the vikings spoke. So to answer the question yes, we do understand it about 60+%. You can probably find some icelandic scholars who are even more familiar with this type of dialect and they can probably understand it 95+%.