diff --git a/frontends/ycdl_flask/backend/endpoints/video_endpoints.py b/frontends/ycdl_flask/backend/endpoints/video_endpoints.py
index 225ac67..3eb5675 100644
--- a/frontends/ycdl_flask/backend/endpoints/video_endpoints.py
+++ b/frontends/ycdl_flask/backend/endpoints/video_endpoints.py
@@ -1,6 +1,7 @@
 import flask; from flask import request
 
 from voussoirkit import flasktools
+from voussoirkit import stringtools
 
 import ycdl
 
@@ -12,18 +13,18 @@ site = common.site
 @site.route('/mark_video_state', methods=['POST'])
 def post_mark_video_state():
     video_ids = request.form['video_ids']
+    video_ids = stringtools.comma_space_split(video_ids)
     state = request.form['state']
-    try:
-        video_ids = video_ids.split(',')
-        for video_id in video_ids:
-            video = common.ycdldb.get_video(video_id)
-            video.mark_state(state, commit=False)
-        common.ycdldb.commit()
 
+    try:
+        videos = [common.ycdldb.get_video(id) for id in video_ids]
     except ycdl.exceptions.NoSuchVideo as exc:
-        common.ycdldb.rollback()
         return flasktools.json_response(exc.jsonify(), status=404)
 
+    try:
+        for video in videos:
+            video.mark_state(state, commit=False)
+        common.ycdldb.commit()
     except ycdl.exceptions.InvalidVideoState as exc:
         common.ycdldb.rollback()
         return flasktools.json_response(exc.jsonify(), status=400)
@@ -34,14 +35,15 @@ def post_mark_video_state():
 @site.route('/start_download', methods=['POST'])
 def post_start_download():
     video_ids = request.form['video_ids']
-    try:
-        video_ids = video_ids.split(',')
-        for video_id in video_ids:
-            common.ycdldb.download_video(video_id, commit=False)
-        common.ycdldb.commit()
+    video_ids = stringtools.comma_space_split(video_ids)
 
-    except ycdl.ytapi.VideoNotFound:
-        common.ycdldb.rollback()
-        flask.abort(404)
+    try:
+        videos = [common.ycdldb.get_video(id) for id in video_ids]
+    except ycdl.exceptions.NoSuchVideo as exc:
+        return flasktools.json_response(exc.jsonify(), status=404)
+
+    for video in videos:
+        common.ycdldb.download_video(video, commit=False)
+    common.ycdldb.commit()
 
     return flasktools.json_response({'video_ids': video_ids, 'state': 'downloaded'})