I agree, it appears to be the Salvi Apollo. What lends to the wonderful sound is the fact that the harp is very much in tune. So many harpists post video without carefully tuning. The tone of her playing in this video is also wonderful. This artist has done a great job preparing for this piece.
A John also stated, the hall has contributed to the tone here. I personally experienced this natural amplification at the Interfaith Peace Chapel here in Dallas. It really sounded like the harp was amplified!