Transcript of the above video:

As the title of this video suggests, we are discussing passport seizures in the context of arrest. I thought of making this video after reading a recent article from the Bangkok Post bangkokpost.com, the article is titled: Police bar Chinese bribe suspect from leaving Thailand. Quoting directly: "Police seized the passport and blocked the departure of a Chinese journalist arrested for allegedly demanding a multi-million-Baht bribe from a suspected Chinese gangster to arrange for charges against her to be dropped. Deputy National Police Chief Pol Gen Surachate Hakparn (that is 'Big Joke') said on Sunday police had turned down (name is redacted) request to leave the country "to attend a meeting" in Hong Kong. Police prohibited the woman from leaving Thailand because she was a suspect and her passport had to be seized, Pol Gen Surachate said."

So when you are arrested in Thailand, not unlike for example in the United States, they may rescind your passport until such time as a criminal trial has occurred and a verdict has been rendered as to one's innocence or guilt. Now one can request of the Court as perhaps part of bail proceedings, that one be allowed to have their passport returned and one be allowed to leave the Kingdom briefly for example in this case sort of for a business meeting. Again it is at the discretion of the Court whether or not that is going to be allowed. It can also be, well at the time of arrest generally speaking, the police will do that pro forma. They will basically say "look we are going to hold your passport" and then they will deal with your Embassy here locally and explain what's going on and oftentimes then the Consulate, in the case of the American Citizen Services section, the Consulate will often send an Officer down to just check in usually to say "Hey you may want to hire an Attorney", give folks a list of Attorneys, and oftentimes they will assist in sending a message or messages back to one's family for example back in the United States; that is just an example of how the Americans do it but most other Embassies kind of do it similarly. 

But long story short yeah, if you get arrested in Thailand presume you are going to have your passport taken and you are not going to be able to leave until the criminal matter has been resolved.