I don't understand your question - her pronunciations of sinn and féin are pretty standard (féin is widely pronounced with a "h" sound, but it's spelt féin). The "d" in her nímid is clearly slender, so she's not saying "nímud". Except for the well known exception of féin, she's reading that phrase pretty much exactly as you would expect it to be read, just following standard orthography rules, given her dialect/accent.
It's not unusual for the f to be unvoiced - for example in the future and conditional tenses.
But in the case of féin there seems to be a lot of variation. For example, on teanglann, the phrase cheana féin gets an "f" sound in Ulster, but not in Connacht or Munster, while on abair.ie, mé féin and sinn féin get an f sound in Dingle and Connemara, but not in Gweedore.
Thanks, very interesting! Just on the future tense, I was told previously that most Irish speakers wouldn't pronounce the 'f' (or would pronounce it with a 'h' sound), although in the conditional it is pronounced. I guess maybe it's the same as what you're saying about 'féin', in that different dialects do things differently?