This is interesting. I'd never think you can't watch it. The whole program is on S4C International here and slovenia appears in 1:09:54. I bet you'll be able to watch the performance there. The Côr Merched Sir Gâr from much beloved Wales you can hear from 1:28:25.
If I look back to this whole program I can say with certanty it was a festival of long hair as you almost couldn't see any girl/woman with short hair. Interesting thingy.
So I hope you can enjoy this now and all the rest of the program if you feel like to watch the whole competition.
Oh and the second song of Côr Merched Sir Gâr performance - Welsh Lullaby - reminds me to one of Slovenian songs called "Nocoj, pa ho nocoj" (Tonight, oh tonight). Compare and you'll hear. What a coincidence, isn't it? The text with Slovene song is very sad though and talks about the boy who comes to the girl for the last time because he goes to the army for long 7 years.