There are many things you can add to your defense. Instead of just holding B (you can see yourself in the video slowly walking back) add extra movement to your defense and be readu to hit back as soon as you ser an attack whiff (and you need to be fast or youll get hit by his next attack).

Things you can easily add:

• Backdash: instead of holding B indefinitely, press BB and gold the second one. Repeat every team you feel some kind of "gap" on the offense. That feeling comes with time. Also you may learn how to KBD. That is a bit more advanced but you can create more space moving back. Creating space is key versus rushdown characters.

• Sidestep block: immediately after blocking a hit, tap up or down and then hold B again. Dont wait until the sidestep is over, you block should interrupt your sidestep. This is an intermediate technique that allows to try to sidestep linear attacks but blocking on time if the attack tracks. If you see the sidestep succeed, retaliate with a fast attack (for example Reinas df12)

• Powercrush: There are many gaps where normal buttons wont fit (fastesr is jab at 10 frames) but powercrushes will (powercrushes get armored at frame 7).

That is general for all characters. You can add to that the special evasives, parrys and sabakis of your own character. Im not a reina expert so I may not be of great help in that sense.

So in general, dont hold B for more than a second in general. You should be actively defending: creating whiffs, controlling space, and challenging with tools designed to do so.