Imagine their NIYATS, definately it is not to pray for ALLAH, it is pray to disturb.
Imam and followers of this particular namaz are committing a huge Gunnah/KUFR
May ALLAH keep us , our kids and every member of the nation safe from these shaitans.
Don't be so arrogant to judge someone for things that aren't yours to judge. You don't know people's intentions and you have no knowledge of the unseen. Only Allah judges our prayers and know what is in the hearts of men and their intentions.
As far as what they did is concerned. The blame is on everyone present in that hall. First off, they should've been stopped by force by the people who were sitting or standing there enjoying and laughing at it and told that this isn't the proper way. Secondly, why was the speaker blabbering when he was seeing those people prepare for Namaz. He should've dismissed the proceedings right away if he couldn't stop them.
When you see some wrong being committed, as a Muslim you've three choices. Stop it by force, speak about it or consider it wrong. Laughing about it and enjoying it isn't okay.
At the very least the people who saw it and considered it wrong should've left if they couldn't stop it or speak against it.
I don't know what happened afterwards, those people should've been scolded, ridiculed and told the right way and questioned why they did what they did.
So the blame is on everyone. If i was present there, trust you me, i would've thrown a shoe at them for ridiculing the assembly, the constitution of Pakistan and making Namaz such a light thing instead of laughing like an idiot and enjoying it.
