Can I legally upload a video taken in my home into my social media account?

There are many social media services, and you do not say which one. Each social media type has a terms of service that you should read. You are probably not allowed to post a video that shows any person besides yourself unless you have permission from that person. Since you definitely do not have permission to post a video of these people, then it is illegal for you to post. It sounds like you think your cabinets are damaged. If the cabinet is actually damaged, you should ask the company to come out and do a touch up, such as sanding or stain, etc., to make it so it is not noticed.

This depends on many factors. In Washington, one is not allowed to record audio without permission if there is a reasonable expectation of privacy. The same goes for video on the federal level. In this case, it doesn't sound like these people should have a reasonable expectation of privacy. Is the recording just video or audio and video? The granite company might have a case for defamation. However, a valid defense against a claim of defamation is that the statements are true. In this case, a claim for defamation wouldn't hold water. Finally, sometimes contracts will contain an anti-disparagement clause. Or in rare cases, a copyright clause in relation to the subject matter of the contract. These might grant the granite company some relief, so it is a good idea to have a look at the agreement. Of course, it's hard to make an exact determination given the brevity of facts. You are welcome to contact me if you would like to have this issue analyzed sufficiently.

Ridiculing a person or company via video on social media is a juvenile way to respond to your problem. Address the problem directly with the company. If you aren't satisfied with the response, notify accreditation or reputation-sharing organizations such as the Better Business Bureau or Angie's List or a licensing entity such as the state or city. You can also file a suit against the company.