CREATE TABLE table_25721_4 (_number_of_discs VARCHAR, release VARCHAR)

How many DVDs where were in the complete collection series 1-8 with extras?
SELECT _number_of_discs FROM table_25721_4 WHERE release = "The Complete Collection Series 1-8 with extras"
SELECT "_number_of_discs" FROM "table_25721_4" WHERE "The Complete Collection Series 1-8 with extras" = "release"