For example, how can I search for a particular ‘google search’ from the web history results?
Browse to the appropriate area under Results (for example, “Results-Extracted Content-Web Search”)
Also, in general how can I globally search for something across the results of all ingest modules?
Do you mean how to do a keyword search? That is covered in Section 9.
You can right click on a field within Extracted Content (for example, “Text” within “Web Search”) and show rows based off of filtering, if that answers your question.