Bruno was not willing to talk. At worst, Angelo knows everything. Is there a point in admitting it? The best scenario is that Angelo does not know anything, however, that is not an option because Angelo is definitely aware that Bruno approached Emma and interacted with her.
Angelo saw that Bruno has no intention to say his side of the story, so Angelo did the only thing he could: he played the last video.
The video on the laptop was from the safehouse which showed Bruno's talk to JoAnna: when he admitted plotting against Angelo by using Emma to take over Angelo's position, and eliminating all Angelo's children when he achieves his goal.
"Say something…", Angelo urged Bruno when the video ended. "Tell me that it's not true. Tell me that it is fake. Tell me that the man on the video is not you!"
Bruno looked at Angelo with an unreadable expression. "What would you do if I deny this as true?"