Navy statement pretty much described it with words "lates in Indian Navy"... It appears to be Kalvari-class based on Scorpene-class sub.... from all over the look... Video contains two footage like in start it shows a file video of Kalvari-class and then detection video while sub was made to come out of water (night vision recording). People here may be confused with file footage that sub was already on the water but that video is for reference only. Original video of detection is in B&W (Night Vision).
Read above post... Two footage are edited in start, 1) of file video for reference and then, 2) original detection footage in night vision.