This video, makes the following claim, as aired on Fox News:
[Obama] did bow to the Muslim King, while he did not do it to the British Queen of England, and by bowing he showed the world that "I am subservient, I do bow down to you as a Muslim King." Something that no other president has done with Saudi Arabia. [5:26]
... it made an American president, for the first time in history, bow to a Muslim King. [6:29]
The video makes many other claims, most of which are far too subjective to be worthy of consideration, let alone on-topic here.
I'm interested in only the following claim: Obama is the first U.S. president to bow to a Muslim King.
And I see two areas of easy contention. The first being the definition of a bow. Does the gesture shown in the video carry the significance of a "bow" in Muslim cultures?
And if what Obama did is considered a bow in the relevant culture, is he indeed the first president to have done it?
For bonus points, have other U.S. presidents bowed to other Muslim world leaders who did not carry the title of King?