Fix problem with quality while resolving videos, do not allow direct links to video

src/Podsync/Controllers/FeedController.cs

@@ -46,6 +46,11 @@ namespace Podsync.Controllers
         {
             var linkInfo = _linkService.Parse(new Uri(request.Url));
 
+            if (linkInfo.LinkType == LinkType.Video)
+            {
+                throw new ArgumentException("Direct links are not supported, you should provide group, channel or user link");
+            }
+
             var feed = new FeedMetadata
             {
                 Provider = linkInfo.Provider,

src/Podsync/Services/Resolver/YtdlWrapper.cs

@@ -50,9 +50,9 @@ namespace Podsync.Services.Resolver
             switch (resolveType)
             {
                 case ResolveType.VideoHigh:
-                    return "best[ext=mp4]/low[ext=mp4]";
+                    return "bestvideo";
                 case ResolveType.VideoLow:
-                    return "low[ext=mp4]/best[ext=mp4]";
+                    return "worstvideo";
                 case ResolveType.AudioHigh:
                     return "bestaudio[ext=m4a]/worstaudio[ext=m4a]";
                 case ResolveType.AudioLow: