On the farm
In a comment, Fabian said, "A good answer should provide the laws and regulations involve" -- although it's not easy to prove that no such laws exist, here are two relevant quotes:
From the Humane Society of the United States:
Q. Aren't there laws that protect farm animals from abuse?
From life on a factory farm to death at a slaughter plant, animals raised for meat, eggs, and milk suffer immensely. And, as shocking as it may be, much of the abuse these animals endure is often perfectly legal. There are no federal animal welfare laws regulating the treatment of the billions of "food animals" while they're on the farm. Further, while all 50 states have cruelty statutes, most explicitly exempt common farming practices, no matter how abusive.
From USDA's Animal Welfare web site:
Farm Animals are regulated under the Animal Welfare Act (AWA) only when used in biomedical research, testing, teaching and exhibition. Farm animals used for food and fiber or for food and fiber research are not regulated under the AWA.
Although there are no federal laws, Wikipedia says that,
Several states have enacted or considered laws in support of humane farming.
The five laws (from five States) listed in this section of Wikipedia all pertain (only) to use of gestation crates.
There's a compendium of all State laws listed here (which I haven't read).
The sidebar of this USDA Animal Welfare page lists the Federal laws, which are:
- Animal Welfare Act
- Horse Protection Act
- Humane Methods of Slaughter Act
- Other Federal Laws
- Twenty-Eight Hour Law
Reading this list, it does seem to be true that there are no Federal laws which condemn cruelty to farm animals before they are taken for slaughter.
On slaughter
There is a Humane Methods of Slaughter Act:
Originally passed in 1958, the law that is enforced today by the USDA Food Safety and Inspection Service (FSIS) was passed as the Humane Slaughter Act of 1978. This Act requires the proper treatment and humane handling of all food animals slaughtered in USDA inspected slaughter plants. It does not apply to chickens or other birds.
Contact the USDA Humane Handling Ombudsman if you have a humane handling related comment or concern or wish to file a complaint.
On at least one occasion, the USDA has "suspended" a slaughterhouse, after an "undercover investigator" from an animal welfare group took some video and sent it to the USDA: USDA suspends slaughterhouse after video appears to show animal cruelty says,
The USDA suspended inspections at the Hanford-based company, effectively halting slaughter operations there.
Company officials have not seen the video, Brian Coelho, president of the Central Valley Meat Co., said Tuesday. He said he was "extremely disturbed" to learn that inspections were suspended.
"Our company seeks to not just meet federal humane handling regulations, but to exceed them," Coelho said in a statement.
USDA inspections are apparently insufficient to detect or prevent all instances of cruelty: I say that because at least one animal welfare group claims to have discovered (and has corresponding video) several instances of 'cruelty' over the years. I presume there are other instance of cruelty, undiscovered, or discovered by other animal welfare groups. Some of these investigations result in criminal charges being laid.
Earlier I said "On at least one occasion" (because I only provided one link to a news article), but this document shows that in 2008 and 2009, there were 80 or 90 "suspensions" per year, issued to federally inspected plants for violations of humane handling and humane slaughter regulations. And, perhaps it is possible or true to say that USDA inspectors do or have "condoned" cruelty: ibid says, on its first page,
[...] These incidents happened despite the continual on-site presence of USDA inspection personnel and the performance of periodic third-party humane slaughter audits at the plant.
There are allegations (which may be so self-evident as to need no proof) that the USDA is more concerned with "food safety" than with "humane killing".
Reporting violations to the USDA
On the subject of "food safety", the problem at the Canadian XL Foods meat packing (slaughterhouse) was that the workers were too hurried: for example The Globe and Mail's XL Foods workers feared raising food safety concerns, union says article wrote,
Mr. O’Halloran also called for whistleblower protection for workers like those at XL who saw safety standards lapse as a result of what the union describes as an impossibly fast pace of work coupled with inadequate training.
“The line speeds, when they get up high, you don’t have time to clean your knife properly,” he said. “If the line speed is too great, you cheat. You don’t have enough time to do it. And, consequently, you are not doing all the things [required for] cleanliness.”
Apparently it's not easy to be a whistleblower:
Canadian meat industry workers are in the same boat as American meat industry workers in that they lack whistleblower protections – key legal safeguards that would enable problems to be made known (and hopefully addressed) without punishing the messenger.
The allegation that cruelty happens, and is not reported by the workers involved, finds some support in articles like this one.
However Anti-Whistleblower Bills Hide Factory-Farming Abuses from the Public suggests that anti-whistleblower ("ag-gag") bills have been introduced but not passed; so apparently it is still legal (per the First Amendment which allows journalists to report) to produce videos like the one you cited in the OP.