transcode checker: longer retry while waiting for videos to finish

but still check db often.
This prevents us from using too much api quota on these checks,
while still letting us spot new videos quickly.

cutter/cutter/main.py

@@ -400,8 +400,9 @@ class Cutter(object):
 
 
 class TranscodeChecker(object):
-	NO_VIDEOS_RETRY_INTERVAL = 5
-	ERROR_RETRY_INTERVAL = 5
+	NO_VIDEOS_RETRY_INTERVAL = 5 # can be fast because it's just a DB lookup
+	FOUND_VIDEOS_RETRY_INTERVAL = 20
+	ERROR_RETRY_INTERVAL = 20
 
 	def __init__(self, youtube, dbmanager, stop):
 		"""
@@ -428,12 +429,11 @@ class TranscodeChecker(object):
 					continue
 				self.logger.info("Found {} videos in TRANSCODING".format(len(ids)))
 				ids = self.check_ids(ids)
-				if not ids:
-					self.wait(self.NO_VIDEOS_RETRY_INTERVAL)
-					continue
+				if ids:
 					self.logger.info("{} videos are done".format(len(ids)))
 					done = self.mark_done(ids)
 					self.logger.info("Marked {} videos as done".format(done))
+				self.wait(self.FOUND_VIDEOS_RETRY_INTERVAL)
 			except Exception:
 				self.logger.exception("Error in TranscodeChecker")
 				# To ensure a fresh slate and clear any DB-related errors, get a new conn on error.