Part 2 of this short documentary continues to explain the different designs of racquet to suit different styles of player.
For example if you are a backhand player, you should pick a racquet that has a lighter racquet head. The lighter racquet head allows you to swing faster which helps in clearing the shuttle with your backhand.
For an offensive player, you may prefer a racquet with a heavier head to help you generate stronger smashes.
It also talks about how to choose the proper tension and thickness of badminton string based on your style of play. In short, it is recommended that you string it between 24 and 26 lbs of tension for recreational player. Unless you are a professional player, it is better not to string it above 30 lb. At that tension, it is good for smashes but you are giving up a lot in control. Thus 24 to 26 lbs of tension is the sweet-spot.
Lastly, it talks about the shuttlecock or birdie. If you don't know the difference, goose feather shuttlecock is better than duck feather because the feather is thicker. Thicker feather essentially is the main factor in maintaining consistent flight. Thicker feather shuttlecock is also more durable.
Enjoy the clip!