New objects, e.g. Cables and Doglegs, are created on whichever layer is shown in the Layers dropdown box, so in answer to your question, yes, that object - but that object alone - will be created on the video layer. The layers of other objects are not affected by the creation of a new object.Symbols typically exist across many layers, with video IOs on the Video Circuit Path layer, audio IOs on Audio Circuit Paths and so on. Use of the Symbol Wizard places all IOs on the appropriate layer.