diff --git a/cutter/cutter/main.py b/cutter/cutter/main.py
index 162840b..56ae5dc 100644
--- a/cutter/cutter/main.py
+++ b/cutter/cutter/main.py
@@ -692,9 +692,6 @@ UPDATE_JOB_PARAMS = [
 	"thumbnail_image",
 	"thumbnail_last_written",
 ]
-UpdateJob = namedtuple('UpdateJob', [
-	"id",
-] + UPDATE_JOB_PARAMS)
 
 class VideoUpdater(object):
 	CHECK_INTERVAL = 10 # this is slow to reduce the chance of multiple cutters updating the same row
@@ -755,12 +752,20 @@ class VideoUpdater(object):
 									assert False, "Bad thumbnail mode: {}".format(job.thumbnail_mode)
 								updates['thumbnail_image'] = thumbnail_image
 							new_hash = hashlib.sha256(thumbnail_image).digest()
-							if job.thumbnail_last_written != new_hash:
+							if bytes(job.thumbnail_last_written) != new_hash:
 								self.logger.info("Setting thumbnail for {}".format(job.id))
-								self.backend.set_thumbnail(job.video_id, job.thumbnail_image)
+								self.backend.set_thumbnail(job.video_id, thumbnail_image)
 								updates['thumbnail_last_written'] = new_hash
+							else:
+								self.logger.info("No change in thumbnail image for {}".format(job.id))
 					except Exception as ex:
-						self.logger.exception("Failed to update video")
+						# for HTTPErrors, getting http response body is also useful
+						if isinstance(ex, requests.HTTPError):
+							self.logger.exception("Failed to update video: {}".format(ex.response.content))
+							ex = "{}: {}".format(ex, ex.response.content)
+						else:
+							self.logger.exception("Failed to update video")
+
 						self.mark_errored(job.id, "Failed to update video: {}".format(ex))
 						continue
 
@@ -788,14 +793,15 @@ class VideoUpdater(object):
 		""").format(
 			sql.SQL(", ").join(sql.Identifier(key) for key in UPDATE_JOB_PARAMS)
 		)
-		return [UpdateJob(**row) for row in query(self.conn, built_query)]
+		return list(query(self.conn, built_query))
 
 	def mark_done(self, job, updates):
 		"""We don't want to set to DONE if the video has been modified *again* since
 		we saw it."""
+		updates['state'] = 'DONE'
 		built_query = sql.SQL("""
 			UPDATE events
-			SET state = 'DONE', {}
+			SET {}
 			WHERE state = 'MODIFIED' AND {}
 		""").format(
 			sql.SQL(", ").join(
@@ -804,12 +810,13 @@ class VideoUpdater(object):
 				) for key in updates
 			),
 			sql.SQL(" AND ").join(
-				sql.SQL("{} = {}").format(sql.Identifier(key), get_column_placeholder(key))
+				# NULL != NULL, so we need "IS NOT DISTINCT FROM" to mean "equal, even if they're null"
+				sql.SQL("{} IS NOT DISTINCT FROM {}").format(sql.Identifier(key), get_column_placeholder(key))
 				for key in UPDATE_JOB_PARAMS
 			)
 		)
 		updates = {"new_{}".format(key): value for key, value in updates.items()}
-		return query(self.conn, built_query, **job, **updates).rowcount
+		return query(self.conn, built_query, **job._asdict(), **updates).rowcount
 
 	def mark_errored(self, id, error):
 		# We don't overwrite any existing error, it is most likely from another attempt to update
diff --git a/cutter/cutter/upload_backends.py b/cutter/cutter/upload_backends.py
index b4b2968..bb4de2f 100644
--- a/cutter/cutter/upload_backends.py
+++ b/cutter/cutter/upload_backends.py
@@ -258,9 +258,10 @@ class Youtube(UploadBackend):
 
 	def set_thumbnail(self, video_id, thumbnail):
 		resp = self.client.request('POST',
-			'https://www.googleapis.com/youtube/v3/thumbnails/set',
+			'https://www.googleapis.com/upload/youtube/v3/thumbnails/set',
 			params={'videoId': video_id},
-			body=thumbnail,
+			headers={'Content-Type': 'image/png'},
+			data=thumbnail,
 		)
 		resp.raise_for_status()
 
diff --git a/thrimshim/thrimshim/main.py b/thrimshim/thrimshim/main.py
index d671531..ccdc2f8 100644
--- a/thrimshim/thrimshim/main.py
+++ b/thrimshim/thrimshim/main.py
@@ -210,6 +210,8 @@ def get_row(ident):
 			return value.isoformat()
 		if isinstance(value, datetime.timedelta):
 			return value.total_seconds()
+		if isinstance(value, memoryview) or isinstance(value, bytes):
+			return base64.b64encode(bytes(value)).decode()
 		raise TypeError(f"Can't convert object of type {value.__class__.__name__} to JSON: {value}")
 	return json.dumps(response, default=convert)
 
@@ -288,6 +290,18 @@ def update_row(ident, editor=None):
 		for transition in new_row['video_transitions']
 	]
 
+	# Convert binary fields from base64 and do basic validation of contents
+	if new_row.get('thumbnail_image') is not None:
+		if new_row['thumbnail_mode'] != 'CUSTOM':
+			return 'Can only upload custom image when thumbnail_mode = "CUSTOM"', 400
+		try:
+			new_row['thumbnail_image'] = base64.b64decode(new_row['thumbnail_image'])
+		except binascii.Error:
+			return 'thumbnail_image must be valid base64', 400
+		# check for PNG file header
+		if not new_row['thumbnail_image'].startswith(b'\x89PNG\r\n\x1a\n'):
+			return 'thumbnail_image must be a PNG', 400
+
 	conn = app.db_manager.get_conn()
 	# Check a row with id = ident is in the database
 	built_query = sql.SQL("""