Isn't it bad practice to use HTML tables to style a form?

Yeah, it generally is not the greatest way. CSS Frameworks have really made this easier for us.

To be fair, he isn't using a table for the whole page layout, just the form, which isn't as bad, but it still could be better.

If I was to take a guess, the choice here was made to do it this way to keep the CSS to a minimum so this lesson could be focused on the PHP side of it. That's just my guess though.

The use of tables is 100% correct, and shows a deeper understanding of the table element than those who espouse only using tables to display grids of numbers.

From the W3C (emphasis mine): "The HTML table model allows authors to arrange data -- text, preformatted text, images, links, forms, form fields, other tables, etc. -- into rows and columns of cells."

Also from the W3C: "Tables should not be used purely as a means to layout document content as this may present problems..."

Randy is using tables as intended. His form fits the table model very well (it can be logically and consistently divided into rows and columns). [For non-tabular form designs, this would not hold true, so I would stop short of saying it is always OK to encapsulate forms within tables.]

Think of Randy's form as a grid (dare I say, 'table') containing data pertaining to customer feedback (because it is). Column 1 contains labels identifying the type of feedback, column 2 contains the feedback itself (in this case user collected instead of populated from a database or web service). It is not hard to imagine a third column containing validation messages (which is simply meta-data regarding the appropriateness of the values entered in column 2).

In other words, Randy used a table to display tabular data. The fact that this happens to provide an extremely easy mechanism to enforce the desired layout doesn't make it incorrect.

For a more succinct statement of this argument, I refer you back to Randy (in the video in question):

"You may have heard something about not using tables in your HTML. The key is not to use tables for layout. If you have a 3-column layout, for example, don't use an HTML table for that. But if you do have tabular data, then a table element is perfectly acceptable."

On a side note, there is a good reason not to always use tables for this purpose, but it has nothing to do with whether or not that usage is semantically correct and consistent with web standards (true and true). If this form were displayed on a small enough screen (phone or perhaps a small tablet in vertical orientation), the table will force the labels and form fields to stay side by side. Using div elements and CSS, we could dynamically shift these elements into a single column to better accommodate small screen sizes (this can be pulled off using separate tables for each row...but I wouldn't). As a caveat to this caveat, though, note that the page in question is NOT mobile-friendly by design...the header and footer are cut off at screen sizes below 980px, so the point about forms and small screen sizes is moot here.