Hm... It's very basic for tutorial 1.
I really like the effort
The window skin for the menu really hurt my eyes though >.<
First of all, that bee with the text... I almost didn't kill him.
I suggest you do a check of the total number of enemies in the map at the start and one of the total number of enemies in the current map. Then when the latter is less than the former by 1, have it show the text then a self-switch.
Second... you should have at least tell the controls. Since I customized my game with custom controls, I had to think about what each control was... lol
I'd also like to see the HUD... since I didn't know how much HP I had o.o
Okay then with the boss.
"Well, well, well... If it isn't the hero himself." Cassandra is a girl o.o
"You can now not use the running key and he is now an enemy." Veeerrry awkward sentence. Fix it by using, "You now cannot use the running key, and he is now an enemy. (Cannot is one word)
Suggestions for other tutorials:
Scripter's tutorials - tell how you are able to make Blizz-ABS add-ons, different utilities a scripter can use (like the version check), and maybe an example of an add-on already made.