Never mind, I figured it out after sending the email: http://localhost:8983/solr/select?q=level2categories:%22Artists\|Direct%20from%20the%20Artist%22&group=true&group.field=groupby&group.main=true&facet=true&group.facet=true&facet.field=level1categories&facet.field=level2categories&rows=0
I needed to enclose the value in double quotes and also have escape the | sign with \. Thanks.
