Well, finally i got help from devteam.
They help me export video from source.
Actualy, i suppose that problem appears after moment when my RAID volume with recordings became "degrade status".
One HDD failed. RAID chip is on motherboard so it have poor speed and no cache or BBU.
RAID volume was under hi load with recording ang at the same moment tried to rebuild itself...
Some bytes desappear i think)
Use only good raid controllers))
