Make pbos owner of additional video files.

NOTRY=True

Review URL: https://codereview.webrtc.org/1724303005

Cr-Commit-Position: refs/heads/master@{#11781}
diff --git a/webrtc/OWNERS b/webrtc/OWNERS
index b806e21..057b563 100644
--- a/webrtc/OWNERS
+++ b/webrtc/OWNERS
@@ -6,3 +6,5 @@
 per-file *.gypi=*
 
 per-file BUILD.gn=kjellander@webrtc.org
+
+per-file *video*.h=pbos@webrtc.org