Haraldr speaks Old Norse although the pronunciation is a bit too modern (Icelandic) at times.
Haraldr Sigurðarsonr stendr fyrir þér. Aldregi var víkingr slíkr lands né lagar. Hahaha, ertu hræddr?
Harald Sigurdson stands before you. Never was there such a viking on land or sea. Hahaha, are you afraid?
https://youtu.be/Co6euiRdBF8?t=11m14s
Til sigurs! Til halla Óðins!
To victory! To Odin's halls!
This is anachronistic since Haraldr was a Christian like most Norwegians since the late 10th century.
If anyone finds more lines I can transcribe and translate them.
Edit: watching it again the pronunciation is not "a bit" too modern. The speaker is clearly an Icelandic speaker imitating Old Norse based on an incomplete understanding of how it sounded. The vowels 'y' and 'æ' for instance are pronounced flat out wrong as they have changed quite a bit from Old Norse to modern Icelandic but 'halla' when Haraldr attacks is unmistakably not Icelandic but a more archaic ON pronunciation.