I haven't seen the video, so I can only deal with the points you mentioned.
In cases like these, words such as "stealing" or "plagiarising" are often used by Islam critics. Usually, such usage is incredibly fallacious.
Anything that the Prophet did and as soon as it is found to have also been done by a previous people, shouts of "stolen" start resonating.
According to some narrations on the matter, the "Ashura fasts" were observed following the practice of the jews.
Narrated Ibn `Abbas:
When the Prophet (ﷺ) arrived at Medina, the Jews were observing the fast on 'Ashura' (10th of Muharram) and they said, "This is the day when Moses became victorious over Pharaoh," On that, the Prophet (ﷺ) said to his companions, "You (Muslims) have more right to celebrate Moses' victory than they have, so observe the fast on this day."
Source:
https://www.sunnah.com/urn/43570There does not appear to be anything wrong here.
As far as I know, the Qur'an
never promises heaven for people who associate partners with Allah. The term "Sabean" was used for a variety of people, some of them believed in Allah, while some had polytheistic beliefs.
The word saabi’ (Sabian) is derived from the verb saba’a which refers to the action of leaving one religion and entering another.
Source:
https://islamqa.info/en/49048Regarding Ramadan, we
know from the Qur'an that this practice was enjoined on previous nations by Allah. Additionally regarding the
Salaat, from Hadeeth and Jewish/Christian scriptures we find evidence that previous prophets and nations also performed similar prayers (with prostrations etc.). Some scholars even go to the extent of arguing that the previous prayers and the Muslim prayers are almost identical. In either of these cases, these practices being also enjoined on the Muslims shouldn't be an issue.
The arguments appear to have been taken from Robert Morey's work to which detailed counter-arguments are made here:
Three part article:
http://www.loonwatch.com/2011/08/the-allah-is-the-moon-god-nonsense-could-be-the-stupidest-anti-muslim-conspiracy-theory-yet-page-i/Probably more technical article:
http://www.islamic-awareness.org/Quran/Sources/Allah/moongods.htmlAdditionally, you can also use some custom Google search engines limited to Islam-related websites to more easily research such topics:
search.islamwiki.org -
bemuslims.weebly.com/muslims-search-engine.htmlRegards,