Add a file related Sequence menu to the VSE header.

seqence_menu.py

import bpy

class SEQUENCER_MT_SequenceMenu(bpy.types.Menu):
    bl_idname = "SEQUENCER_MT_sequence_menu"
    bl_label = "Sequence"

    def draw(self, context):
        layout = self.layout

        layout.operator_context = 'INVOKE_REGION_WIN'
        layout.operator("sequencer.refresh_all", text="Refresh All")
        layout.operator_context = 'INVOKE_DEFAULT'

        layout.separator()
        layout.operator("sequencer.movie_strip_add", text="Import Movie")
        layout.operator("sequencer.sound_strip_add", text="Import Sound")
        layout.operator("sequencer.image_strip_add", text="Import Image/Sequence")

        layout.separator()
        props = layout.operator("render.opengl", text="Export Sequence")
        props.animation = True
        props.sequencer = True
        layout.operator("render.opengl", text="Render Image").sequencer = True

        layout.separator()
        layout.operator("sound.mixdown", text="Export Audio Mixdown")

        layout.separator()
        layout.operator("sequencer.export_subtitles", text="Export Subtitles")



def prepend_sequence_menu(self, context):
    self.layout.menu("SEQUENCER_MT_sequence_menu")
    self.layout.separator()

def register():
    bpy.utils.register_class(SEQUENCER_MT_SequenceMenu)
    bpy.types.SEQUENCER_MT_editor_menus.prepend(prepend_sequence_menu)

def unregister():
    bpy.utils.unregister_class(SEQUENCER_MT_SequenceMenu)
    bpy.types.SEQUENCER_MT_editor_menus.remove(prepend_sequence_menu)

if __name__ == "__main__":
    register()