if it’s the first vid that comes up in search results, then the explosions are caused by the sigil of fire. the person is also level 80, which means they have access to more traits that can help the fight go quicker. they also probably have a full set of level 80 gear with runes and such. because of all these things there will be some differences in the fight you see and what you experience.
try using the number 2 skill instead of just hitting the undead, it helps a lot, especially the second part of the skill (if you press it twice), which has an evade.
70 ‘mains’ and waiting for more slots
| 61 Asura | 5 Charr | 2 Norn | 1 Human | 1 Sylvari |