Retired English Teacher
The first couple of times I listened, I had him down as a native speaker, but the more I listened, the more I went with robarocamel and Tdol. My phonetics ear-training was long ago, and I can't put my finger on it, but there is something about his /ð/ (definitely) and his /r/ (sometimes) that disturbs me.
My native English instincts tell me the speaker sounds like a native English speaker because his speech follows the pronunciation patterns of English--not USA based, mind you, but British based.
His pronunciation of 'seas' sounds English to me, not Standard British English, but then again, there are so many dialects to take into account as well as the speaker's own idiolect to consider. On that note, and this may sound odd, his pronunciation of 'seas' reminds me of how a sailor would say it, which could mean the speaker's pronunciation is in part influenced by the text itself.