Paying attention to other sentences read by this speaker, he seems to voice all voiceable consonants after "an". (Voicing is the process by which C becomes G, T becomes D, etc.) Interesting. I wonder if it's a local accent or if the other speakers do it too and I hadn't noticed.
Look at the article Nasalisation 2 or Why am I married to ə NɯNʲə agam? on the Akerbeltz Wiki.
Some dialects of Scottish Gaelic have something that resembles Irish eclipsis (even though the proper eclipsis as a grammaticalized mutation disappeared) – some of them voice the voiceless aspirated stops (/t/ [tʰ], /p/ [pʰ], /c/ [kʰ] change to [d(ʰ)], [b(ʰ)], [ɡ(ʰ)]) and the unaspirated ones (/d/ [t], /b/ [p], /ɡ/ [k] change to [d] or [n], [b]); and some other dialects (Lewis, Skye) fully nasalize them (/t/ [tʰ], /p/ [pʰ], /c/ [kʰ] change to [nh], [mh], [ŋh], /d/ [t], /b/ [p], /ɡ/ [k] change to [n], [m], [ŋ]) after any nasal consonant (not just after an).
Hence an cù might sound [əŋ ɡuː] or even [əŋhuː] and an taigh might be [əN d(ʰ)ɤj] or [əNhɤj], while an duine [əN dɯNʲə] or even [əNɯNʲə] as if spelt an nuine.
But it does seem to depend on dialect.