When I hear politicians and actors stating they believe Dr. Ford's testimony, do they realize she hasn't provided any testimony?

What exactly are the basing their belief on

Confirmation bias… And nothing else, they want her to be telling the truth because she bats for their team

Most have not been saying they believe her. Instead, they are saying these allegations should be investigated. And why not? It's a lifetime position. Why the big hurry? Are they afraid more allegations will come out? Are they afraid it will be proven?

When I hear politicians and Trump stating they believe Kavanaugh's testimony, do they realize he hasn't provided any testimony?

What exactly are the basing their belief on

See what I did there?

Well, there's the detailed written account she originally provided, as well as a polygraph. But sure, maybe she'll change her mind before Thursday.

Democrats believe, and get their marching orders from the Democrat press sex criminals.

Does not matter, the Crime is proven by the Accusation alone.
Nobody would accuse anyone of such a crime where it not true.
Get the Rope and hang him… Don't need no trial.

Words like "testify" and "testimony" have meanings other than their meanings as official statements given witnesses in a criminal proceeding.
Example: Support groups often have someone "testify" or "provide testimony" about their own experiences.

Their hate for Trump and his pick

Don't bother them. They just "believe".