If the data is in a table in pages you can just cut and paste.
Otherwise it would depend what form its in and I doubt there would be a generic video.
If you post your specific problem here or in the mac apps page you'll probably get some quick help but give some examples of what the data you are trying to convert looks like.
Be aware that before you do the cut-n-paste, to arrange your data in Pages into the proper format so that it can easily "drop into" a Numbers worksheet (or into ANY spreadsheet app).
That is to say, you should use tab characters to define breaks between cells, and a carriage return to define when to drop down to the next row.
You probably want to get rid of any additional formatting in the Pages document first, as this may not transfer across properly. All you want to see are tabs and carriage returns in addition to the text itself.
You also need to make invisible formatting characters visible in Pages, so that you can closely examine the document before you attempt to copy/paste the data -- to avoid unintended results...