1- As for the video, it has two fundamental problems. The first is that a lot of the statements by those speakers have been taken out of context. They show you 5 seconds. Do you know what the speaker was saying before that? Is he refuting something? Is he explaining it? Is he endorsing it? I do know some of the speakers in the video and have seen the full lecture and it has been taken out of context. As for some of the other speakers, yes what they say is objectionable and inappropriate, but these speakers don’t represent Shia Islam. They represent a small extremist segment, and I am not shy to criticize them or even outright condemn them. Is it fair to have your faith weakened based on one video that takes words out of context or brings you statements from speakers who don’t represent the Shia beliefs?
I can send you videos of Sunni speakers who say things that will weaken your faith in the entire religion of Islam. Would that be fair?
2- As for Tawassul, please see this video then if you have any follow up questions let me know:
3- As for the attack on Lady Fatima (a), we have a plethora of hadiths, in Sunni and Shia sources, that confirm an attack happened on her house. This we are certain of. As for the specifics of the attack (exactly what happened, how she was attacked, was her door burned, was she pushed behind the door, etc…), we have clear hadiths in Shia sources that state those specifics. As for Sunni sources, they are very brief and some mention that fire was taken to her door, or that she was threatened if she would not open the door they’d set the door to fire. If you are interested, I can send you those sources.
4- I highly recommend you take a course on Shia beliefs to better understand what we believe and what our arguments are then you can come to a conclusion. All the “shirk” arguments you have heard from the Sunnis have a proper response. I’m happy to share with you a playlist of a course I recently taught on Shia beliefs that addresses all these points academically. If you are interested let me know.
5- Sunni belief has major flaws. I invite you to research the following points:
One: how would the Prophet (s) leave this Ummah without pointing us to his right successor? When he’d leave on an expedition he’d appoint a representative in Medina. But he never made the effort to appoint the representative after him? Is this rationally possible? Doesn’t the Qur’an teach us that Allah chooses the Imam/caliph?
Two: Sunnis believe all companions after the Prophet (s) were just and righteous. Doesn’t this contradict the Qur’an when it tells us there were good and bad companions; there were sincere and hypocrite companions?
Three: Who is the Imam in our current time? Didn’t the Prophet say the one who dies without knowing the Imam of his time will die the death of Jahiliyya?
Four: How can we consider Aisha righteous and obedient when she led a war against Imam Ali? Wasn’t he the Imam of her time? Didn’t she directly violate the commands of the Prophet (s) in this regard? And how do Sunnis respect Muawiyah when he also led many wars against Imam Ali?
Five: Didn’t the Prophet say: I leave behind me two heavy things: the Quran and my Ahlulbayt. If you hold on to them you shall never go astray. Do Sunnis take their legal rulings and other teachings from the Ahlulbayt?
There are many other points to research as well.