Your YouTube description didn't indicate important details like your light level. Having ?? for the level only means that it is at least 5 ahead of you. If you're a level 40 and equip beginning game gear, you're still gonna immune shoot any level 10 enemy. What you want to look for is the red number in black box. This tells you the enemy's light is significantly higher and you will have trouble damaging him and even their basic attacks can 1-shot kill you. Orange/Yellow number means the enemy is only at a slightly higher light level. You can put small dents in their health, but they can still 1 or 2-shot kill you. A White number means the enemy's light is equal or below yours.