Thanks for caring so much about pronunciation, most researchers just care about the meaning.
We can not know for sure the exact pronunciation of the Coptic language
Not just because its dead but also it has been alive for so long that its pronunciation must have changed between the centuries
The text you was reading is in Sahidic, Sahidic pronunciation is harder to guess accurately because it died long time ago while Bohairic continued to be used in Church for prayers
Even Bohairic's original didn't survive and church replaced it 200 years ago with a westernized pronunciation (the one you are using in the video you made)http://en.wikipedia.org/wiki/Coptic_pronunciation_reform
You can watch some videos for the original pronunciation (or at least attempt to get as close to it as possible) in these videoshttp://www.youtube.com/watch?v=IKdHr4YtMzUhttp://www.youtube.com/watch?v=OGIa4steqVw