Check WAGTAIL_VIDEOS_DISABLE_TRANSCODE in app startup

wagtailvideos/apps.py

 from django.apps import AppConfig
+from django.conf import settings
 from django.core.checks import Warning, register
 
 from wagtailvideos import ffmpeg
@@ -6,7 +7,10 @@ from wagtailvideos import ffmpeg
 
 def ffmpeg_check(app_configs, **kwargs):
     messages = []
-    if not ffmpeg.installed():
+    if (
+        not ffmpeg.installed()
+        and not getattr(settings, 'WAGTAIL_VIDEOS_DISABLE_TRANSCODE', False)
+    ):
         messages.append(
             Warning(
                 'ffmpeg could not be found on your system. Transcoding will be disabled',

wagtailvideos/templates/wagtailvideos/videos/edit.html

@@ -59,7 +59,7 @@
                 <dl style='margin-top: 0'>
                     {% if video.thumbnail %}
                     <dt>{% trans "Thumbnail" %}</dt>
-                    <dd><img src="{{ video.thumbnail.url }}" /></dd>
+                    <dd><img src="{{ video.thumbnail.url }}" alt="{% trans 'Video thumbnail' %}" /></dd>
                     {% endif %}
                     <dt>{% trans "Filesize" %}</dt>
                     <dd>{% if filesize %}{{ filesize|filesizeformat }}{% else %}{% trans "File not found" %}{% endif %}</dd>
@@ -113,7 +113,7 @@
             </form>
         {% else %}
             <br/><br/>
-            <span class='transcode-error'>{% trans "Ffmpeg is not found on your server. Please install if you wish to transcode videos into an HTML5 video compliant format." %}</span>
+            <span class='transcode-error'>{% trans "Ffmpeg is not found on your server or you have disabled transcodes. Please install and enable transcodes if you wish to transcode videos into an HTML5 video compliant format." %}</span>
         {% endif %}
         {% if tracks_action_url %}
             <h2 class="u-text-transform-uppercase">{% trans "Tracks" %}</h2>