It depends on what kind of records do you mean. In the admin panel, there is a script which allows to save all usernames and emails in CSV file, this could be used further in mass-mailing.
But if you are about all posts, or all topics, you need to be more precise on what records do you mean, how they should be sorted etc. MiniBB's database is quite structured, and if you just save, for example, all posts following by the date of their appearance, I doubt it could be some way useful or readable. So it all just depends on the purpose you'd like to achieve.
To say in advance, we have no such pre-existing script, but if you have cPanel and PHPmyADMIN tool on your server, this could be easily done using it. There are tons of existing scripts for extracting data from mySQL database, we don't have to code something special for this, duplicating others' job.