For checking the transcript: https://www.buzzsprout.com/2379282
Act up
means to behave badly or cause problems. It can refer to both people (especially when they misbehave) and things like machines or devices that stop working properly.
Examples:
1- At the party, Sarah’s dog started acting up, running around and knocking over the drinks!
2- During a concert, Adele’s microphone started acting up, causing some audio issues, and she had to pause for a couple of minutes to fix it.