The bulk updater has a search area so you can find the submissions you want to update.
You can mass select the found submissions using the Select dropdown. In the results list you can also select individual entries for updating by pressing their checkbox on the left side.
Once a submission is selected you can edit its name, the attached homepage and whether it's public or hidden. You can also see the current version of the uploaded file and all content flags set for this mini.
To change the content flags, check "Replace Flags" in the toolbar, then select the appropriate content flags for your selection. You can also enter a new version and changelog info for the new creature file.
If you don't select "Replace Flags", the bulk updater will only update the mod.io metadata, and will not change anything about the uploaded .tsMod files itself.
If you do select "Replace Flags", the bulk updater will update any changes to the mod.io metadata, and download the currently active mod file, add/replace its content flags with the ones selected in the bulk updater, save and reupload the now edited .tsMod (and, if necessary, upgraded) file back to mod.io.
Note: If there are more results than your page size, you can use the page buttons below the toolbars to switch through result pages, but your selection will be cleared when switching between pages!