My understanding is that for all Humax youview boxes it is now possible to delete more than 1 recording at once if they are all in a series folder. It works for me on a DTR-T2100 with the March 2015 Youview software but some Humax boxes were not going to update until this month (April 2015).
Could the FAQ on multiple deletions be updated?
can-i-select-multiple-recordings-to-delete