I can't see any video.
Do I have to do anything in particular???

this is good advice, yet the idea of correcting something means it has to be incorrect to begin with.  i do not think that it is "incorrect" to having a roundness in the spine as i have seen pictures of krishnamacharya practice downdog.  as a matter of fact, he practices jalandhara bandha (or maha bandha) in downdog and his spine is rounded.  i learned this while studying with krishnamacharya's student of 33 years (srivatsa ramaswamiji).  krishnamacharya is mr. iyengar's teacher as well as pattabhi jois of ashtanga vinyasa yoga.

also, sri dharma mittra encourages the bank bend and additional opening of the shoulders in downdog to prepare for other poses that require a backbend bind such as king dancer or one foot king pigeon...  there is no perfect pose.. just our individual expression of such.  as long as there is proper action/movement in the pose and it doesn't hurt, i say you are doing it yoga right.

namaste

ricky tran

www.rickytranyoga.com