Thanks EricJH for reviewing the video and clarifying things out.
It may sometime take less than 5 minutes sometimes to get in.If the ARP cache poisoning attack had succeeded you would still need to crack the encryption. The outdated and now depricated WEP encryption can be hacked that quickly. Most people are no longer using that. WPA/WPA2 takes much much longer.
But when the expert reffered to the 5 minutes he was assuming that he was already inside the network so no need to crack WEP or WAP2 encryption.
So you say that if a person is on the same network as me, he/she could only gain access to my webcam if they exploited vulnerabilities in programs that have doors opened on the network. Therefore keeping windows up to date and CIS overflow protection on is enough to avoid getting hacked?