You have the correct orientation. The large letters down the right side are 祈武運長久 (pray for everlasting luck in battle). The large letters down the left hand side is the name of the person to whom the flag was given, IKUTA Yoshio (other readings possible, but this is the most obvious reading). The rest of the writings are names, and one slogan at around the 1:00 mark:
七生報国 Shichishō Hōkoku (I give all my lives for the country. All my lives means "even if I am reborn 7 times, I will give those lives to the country as well").
There are two other people from the IKUTA family who signed this flag. The rest are mostly fairly common names (Katō, Takahashi, Ishida, etc.). There is one unusual name, 靱矢 (UTSUBOYA) which is quite rare. Mostly found in Tokyo, but also in Shizuoka prefecture.
Just on a whim I googled IKUTA Yoshio, and his name pops up on a Japanese white pages (phone directory) listing. Kind of hard to believe it would be the same person, but the name is slightly unusual so it is a remarkable coincidence.
