I would like to create a link from a "Companies" table to show "Related Contacts" like this. The link would lead to another table (sql query) which is filtered to only show Contacts related to that specific company like this. 

All of your url column pre-filtering examples show the filter term already in the URL like: 

http://www.wpdatatables.com/documentation/table-features/global-search-via-url/?wdt_column_filter[1]=Linz

I REALLY need to be able to create the URL based on whatever value is in the first column, but can't see any way to do it. I see: 

"You can also predefine column filter values for the table in the URL, which may come in handy. For example, when you want to send your client a deeplink with some info from your catalog that is already filtered for him. The URL key that will be parsed by the wpDataTables is “wdtColumnFilter[KEY]” where the KEY is either a zero-based numerical index of the column you want to filter, or an initial header of the column (header or the CSV or Excel table, or MySQL column header for MySQL-based column header), e.g.,"

So how to I get the column filter to work? Merge tag? Placeholder? 

I'm going nuts here. 

Just so I'm clear, the "Contact1" in your example needs to be manually customized for each row? Is there a merge tag that I can put in it's place so the URL can be ready to go once a new row is added?